Low-temperature Crystallization Research Articles

Dual effects of a diamide derivative as nucleator on crystallization kinetics and aggregated structure of biodegradable Poly(ethylene succinate)

A linear diamides derivative-containing organic compound (TMC306) as a nucleator was incorporated into biodegradable poly (ethylene succinate) (PES) to investigate effect of TMC306 on crystallization behavior and aggregated structure of PES. Upon incorporation of TMC306 with lower weight fraction (fTMC306), crystallization temperature (Tc), crystallization rate (k) and degree of crystallinity (Xc) of PES enhanced significantly and crystallization half-time (t1/2) reduced substantially. However, Tc, k and Xc declined progressively in the presence of higher fTMC306. Based on IR results, it suggested that TMC-306 interacts with –CO group of PES and C–O–C group of PES amorphous phase via hydrogen bond. Mechanisms on nucleation of PES and dual effects of TMC306 on crystallization behavior of PES were proposed and discussed in detail.

High Electronically Conductive Tungsten Phosphate Glass-Ceramics.

High electronically conductive tungsten phosphate glass-ceramics have been prepared by the controlled crystallization of binary 60WO3–40P2O5 glass in the temperature range from 700 to 935 °C and for 1 to 24 h. The substantial increase in the conductivity for four orders of magnitude is a result of the formation of electronically conductive W2O3(PO4)2 and WO3 phases. At low crystallization temperature the dominant W2O3(PO4)2 phase is created, whereas at 935 °C for 24 h the formation of semiconducting WO3 crystallites of an average size of 80 nm enhances the conductivity to the highest value of 1.64 × 10−4 (Ω cm)–1 at 30 °C. The course of the crystallization and its impact on this exceptionally high electronic transport of binary tungsten phosphate glass-ceramics has been discussed in detail. Since such highly electronically conductive WO3-based glass-ceramics have a great potential as cathode/anode materials in solid state batteries and as electrocatalysts in fuel cells, it is of interest to provide a novel insight into the improvement of their electrical properties.

A very low temperature (170 °C) crystallization of amorphous-Ge thin film on glass via Au induced layer exchange process in amorphous-Ge/GeOx/Au/glass stack and electrical characterization

We report the realization of polycrystalline (poly)-Ge thin film on glass (insulator) at a significantly low temperature of ~170 °C. We realized it using Au induced layer exchange crystallization scheme in a thin film stack having amorphous (a)-Ge/GeOx/Au/glass structure. The observed crystallization temperature is one of the lowest values reported in the literature. The paper also discusses the interface energetics that drives the crystallization in detail. Au has an extremely low solubility of ~1.3 × 107 cm−3 in Ge at this low processing temperature. The layer exchange process facilitates an effective etching of the Au layer, resulting in a poly-Ge thin film free of contamination from residual Au impurities within EDS’s sensitivity. However, the poly-Ge thin film exhibits a p-type semiconducting behavior, with a moderate doping concentration of ~1.3 × 1017 cm−3, and a low resistivity ~1 Ω cm at RT due to point defects induced acceptor states. The thin film showed a mobility ~50 cm2 V−1-s−1 at RT, highest for a poly-Ge thin film formed at such low temperature. The temperature dependence of mobility indicates a high barrier of ~84 meV at the grain boundaries, which serve as the main scattering mechanism limiting the carrier conduction.

(Invited) Polycrystalline Ge-Based Thin Films with High Carrier Mobility

Low-temperature synthesis of high-performance semiconductor thin films on insulators is a key technology to integrate functional devices into Si-LSIs, flat panel displays, and various sensors surrounding us. Ge and Ge-based semiconductors, such as SiGe and GeSn, have higher carrier mobility and lower crystallization temperature than Si, in addition to good compatibility with conventional Si process. In recent years, Ge-MOSFET mobilities have exceeded those of Si-MOSFETs because of the development of device technologies including gate stacks. Conversely, a thin film structure is preferable to a bulk structure to suppress leakage current derived from the narrow band gap. For these reasons, Ge-based thin films are very promising as a channel material for advanced thin film transistors (TFTs). However, the performance of Ge-TFTs is currently limited by the crystallinity of the Ge thin film itself. To improve the device performance, it is essential to innovate the synthesis technology of Ge thin films on insulators.Generally, a polycrystalline Ge (poly-Ge) layer has a high hole concentration because of defect-induced acceptors and a low carrier mobility due to grain boundary scattering.1 In low-temperature (< 500 °C) solid-phase crystallization (SPC) process, we found that the densification of the amorphous Ge (a-Ge) precursor significantly enlarged the grain size and reduced the grain boundary barrier height of the resulting poly-Ge.2 Based on the finding, we have continuously updated the Hall hole mobility of Ge layers formed on insulators (Fig. 1 (a)).3,4 It is attractive that the hole mobility exceeds that of a single-crystal Si wafer, even though the Ge layers are polycrystalline formed by a simple process. The TFT based on the Ge layer exhibited the highest performance among low-temperature Ge-TFTs.5 Because the densified a-Ge crystallizes even at < 400 °C, a flexible plastic can be used for the substrate.4 An n-type poly-Ge layer with a high electron mobility is also achieved by SPC of a-Ge containing n-type dopants (Fig. 1(b)).6,7 Further, we have demonstrated that the advanced SPC technique is useful for SiGe8 and GeSn9,10 alloys. This technique may be universally applicable to other materials, and is currently being applied to III-V compound semiconductors.In this talk, I will discuss (i) the effects of density modulation and doping in Ge precursors on subsequent SPC and (ii) the composition effects of SiGe and GeSn alloys on the growth and electrical properties.[1] K. Toko et al., Solid State Electronics 53, 1159 (2009).[2] K. Toko et al., Sci. Rep. 7, 16981 (2017).[3] R. Yoshimine et al., Appl. Phys. Express 11, 031302 (2018).[4] T. Imajo et al., Appl. Phys. Express 12, 015508 (2019).[5] K. Moto et al., Appl. Phys. Lett. 114, 212107 (2019).[6] D. Takahara et al., Appl. Phys. Lett. 114, 082105 (2019).[7] M. Saito et al., Sci. Rep. 9, 16558 (2019).[8] D. Takahara et al., J. Alloys Compd. 766, 417 (2018).[9] K. Moto et al., Sci. Rep. 8, 14832 (2018).[10] K. Moto et al., Appl. Phys. Lett. 114, 112110 (2019). Figure 1

Ultra-High Mobility Transistors Via Metal Induced Conductive Region

The amorphous oxide semiconductors (AOSs) such as In-Ga-Zn-O (IGZO) and Zn-Sn-O (ZTO) have been extensively studied as the active layers for thin film transistors (TFTs) in display backplanes due to its high mobility (>10cm2/Vs), transparency, low process temperature and large area uniformity. However, many studies on AOSs have reported that there is trade-off relationship between electrical performance and device stability. Generally, the mobility increases with increasing indium or tin content, while the stability is degraded simultaneously. Furthermore, because the indium is a rare metal and expensive, incorporating indium in active materials is one of the critical reasons for increasing overall process costs. For this reason, the development of an indium-free oxide semiconductor materials with high mobility and stability is continuously required.Recently, (Zn1-xBax)SnO3 (ZBTO) has been reported to be a very stable oxide semiconductor with high electron mobility results from its small effective mass and less defective structure. Based on these desirable material properties, it has been adopted as an active material for cost-effective and high-performance TFTs. Also, in order to improve electrical performance dramatically, an additional metal layers are introduced.The metal capping layers have been reported to improve the performance of TFTs by various mechanisms, including the elimination of the scattering/trapping centers, low-temperature crystallization, and electron injection. However, although many research have been performed to demonstrate the origin of the mobility enhancement by the metal capping layer, the exact mechanism has not been confirmed. Also, former reports of this method showed several drawback such as the induced crystallization and need for stabilization time, which may limit its application on large-area displays.To investigate the effect of metal capping layer, the device was fabricated using In-free active material. The ZBTO active layer were deposited via RF magnetron sputtering on the p++ Si/SiOx substrate. All sample was annealed at 350℃ for 1 hour in air ambient, and patterned using shadow masks. The channel width (W) and length (L) were 800 and 200 μm, respectively. In case of metal capped device, 20 nm-thick Al or Ti metal layer was sputtered selectively between the source/drain electrodes with dimensions W/L = 1300/100 μm.In this work, the formation of conductive region in active layer induced by metal capping layer was suggested as new mechanism of the mobility improvement. Due to the strong oxidation power of Al metal, oxygen deficiency is easily induced in active layer near the interface between Al and ZBTO during Al oxidation. This conductive region in active layer generates free electrons, which can be transported without serious scattering owing to the low defect density of ZBTO. These phenomena were confirmed by TEM and XPS results. As a result, the ZBTO TFTs with an Al metal layer exhibited significantly improved field-effect mobility from 20.8 cm2/Vs to 153.4 cm2/Vs without degradation of other transfer parameters. Furthermore, the ZBTO TFTs showed far superior mobility improvement compared to other conventional oxide TFTs. The carrier transport mechanisms was investigated by 1/f noise measurements, which indicated that carrier transport of ZBTO TFTs with the Al capping layer is enhanced by the reduced bulk trap sites. Moreover, reliability tests including NBS, PBS indicated that the front channel of ZBTO active layer was relatively less affected. Our results indicate that adopt of stable active material with small defect density, in this case ZBTO, is a key factor in the fabrication of metal-assisted TFTs capable of ultra-high performance.

Beol Compatible High-Capacitance Mimcap Structure Using ZrO2 with Enhanced Dielectric Constant

We demonstrate a MIM capacitor structure using ZrO2 for the dielectric layer which exhibits a 25% capacitance increase (from ~43fF/mm2 to >55fF/mm2 for a ~55 Å film) with minimal leakage current increase compared to Hf based dielectrics, extending the usefulness of MIM on-chip decoupling capacitors. The MIM structure, suitable for BEOL processing is TiN/ZrO2/TiN combined with an anneal which is shown to improve the capacitance vs. leakage performance compared to doped and undoped HfO2 based control structures. GI-XRD measurements demonstrate that the capacitance increase corresponds with a phase transformation of the ZrO2 from amorphous to cubic phase, which is shown to have a dielectric constant (k) up to 35. Reliability models based on hard-breakdown (HBD) show that this structure exceeds the end-of-life targets.Servers and high-performance chips have historically relied on on-chip decoupling capacitors (decap) to reduce power supply noise in order to achieve 3 – 5.4 GHz operating frequency. Although packaging decap can be very effective at mitigating low and mid-frequency noise, on-chip decap, such as MIMCAP, is critical for mitigating mid and high-frequency noise. As Fig. 1 shows, an increase in on-chip decap can result in a significant performance benefit, due to their fast response time slowing the fastest droops, giving time for slower response elements to contribute. One method of achieving this increased decap is to increase the k of the material being used as the insulator in the MIMCAP. Following high-k gate dielectric technology, HfO2 and other Hf based dielectric stacks have been used for this layer successfully [1]. But there is a significant difference in the thermal budget that the dielectric is exposed to following the deposition between gate dielectric and MIMCAP applications. The gate dielectric, deposited prior to any metallization, will typically be exposed to a relatively high thermal budget compared to the insulator layer of a decoupling MIMCAP, which is usually placed between wiring levels in the back end of the line (BEOL) [2]. Since the thermal budget after deposition will affect the crystal structure of a material, and different crystal phases of the same material can have dramatically different dielectric constants [3], the actual dielectric constant of a particular high-k material may vary significantly depending on whether it is used as the gate dielectric or as the MIM insulator. In this work, we explore the use of a ZrO2 as the high- k layer for MIMCAP applications and show that its low crystallization temperature enables it to achieve a significantly higher k value compared to HfO2 when processed under BEOL compatible thermal conditions.Fig. 2 shows the development of the high-k phase of a 55 Å ZrO2 film as the anneal temperature is increased. The peaks at 35°, 42° and 52° are the signature of the bottom TiN electrode and do not change with anneals; but the peaks at 30.2° and 50.3° , which are seen to develop as the anneal temperature increases, match with the 111 and 220 planes of the cubic phase of ZrO2. MIMCAPs built using similarly annealed ZrO2 layers as dielectrics exhibit an increase in capacitance as shown in Fig. 3a: there is a slight increase after anneal A, significantly more increase after anneal B, and additional moderate increases after C and D. No such capacitance increase is seen when Hf based dielectrics are used (Fig. 3b). The maximum capacitance is found to be ~56fF/um2 after anneal D compared to ~43fF/um2 for the unannealed device, an increase of more than 25%, while the leakage current remains virtually unchanged at 1V, and increases by <5x at 2V. Fig. 3c graphs the calculated value of k as a function of the thermal budget, confirming that the ZrO2 layer has the property of crystallizing to its high- k phase at temperatures relatively lower than is typical for HfO2. Thus, we can achieve high capacitance with a relatively thick high-k layer, keeping the leakage current low, all while maintaining compatibility with BEOL processing.[1] T. Ando et al., “CMOS Compatible MIM Decoupling Capacitor with Reliable Sub-nm EOT High-k Stacks for the 7nm Node and Beyond,” Tech. Dig. IEDM 2016, pp. 9.4.1 - 9.4.4.[2] K. Fischer et al., “Low-k Interconnect Stack with multi-layer Air Gap and Tri-Metal-Insulator-Metal Capacitors for 14-nm High Volume Manufacturing,” IEEE Interconnect Tech. Conf. 2015, 10.1109/IITC-MAM.2015.7325600.[3] X. Zhao and D. Vanderbilt, “First-principles Study of Electronic and Dielectric Properties of ZrO2 and HfO2” MRS Proceedings, 747. doi:10.1557/PROC-747-T5.2/N7.2. Figure 1

Geochemistry of tetrahedrite group minerals and associated silver paragenesis in the Boguszów baryte deposit, Poland

Primary ore mineralization in the abandoned Boguszów baryte-polymetallic deposit, located in the Intra-Sudetic Depression, was studied by reflected light microscopy and electron microprobe. Ore minerals, occurring as veinlets, irregular aggregates and lenses in baryte veins are hosted by the Upper Carboniferous Chełmiec rhyodacite laccolith. They are dominated by galena, sphalerite (with Cd up to 0.04 apfu) and tetrahedrite group minerals (TGM). Four generations of the TGM were distinguished according to textural features and Ag content: (1) low-Ag tetrahedrite-(Zn) (Ag: 0.22–0.6 apfu), (2) Ag-enriched tetrahedrite-(Zn) and Ag-enriched tetrahedrite-(Fe) (Ag: 0.71–1.45 apfu), (3) members of the freibergite series: “freibergite-(Fe)” and “freibergite-(Zn)” (Ag: 3.21–3.48 apfu; Hg: up to 0.75 apfu), (4) member of the “freibergite-(Fe)” series (Ag: 5.32–5.78 apfu). Several elongated inclusions of Ag-bearing sulphosalts within galena crystals were observed (members of the series “freibergite-(Fe)” and “freibergite-(Zn)”, pyrargyrite and polybasite). These polymetallic silver-bearing ores were mined in Boguszów from the 15th to the 19th century. Additionally, small grains of cobalt-enriched löllingite and gersdorffite were observed, which were formed from fluids sourced from the ultramafic basement. The textural characteristics of the ore, the mineral paragenesis and the chemical composition of individual ore minerals indicate low-temperature crystallization conditions.

Enhancement of CO2 Adsorption Containing Zinc-ion-exchanged Zeolite NaA Synthesized from Rice Husk Ash

Carbon dioxide is main causes the greenhouse effect and it contributes to global warming. Zeolite NaA is an excellent adsorbent among other materials but its potential as a carbon dioxide adsorption still needs to be developed. Therefore, this research was to synthesize zeolite NaA from rice husk ash under different temperatures and crystallization times. The synthesized zeolite NaA was modified with zinc by an ion exchange method. Adsorbents were tested for the carbon dioxide adsorption at different operating temperatures and flow rates. The results showed that the zeolite NaA was successfully synthesized from rice husk ash under optimal conditions of the crystallization temperature at 333.15 K and time for 2 h. The zeolite NaA can be synthesized at low crystallization temperature and time resulted in this adsorbent has low cost while achieving high efficiency. The results of zeolite NaA modification with zinc playing a key role to increase the BET surface area, micropore volume and total pore volume resulted in an increase of carbon dioxide adsorption capacity. High carbon dioxide adsorption at 89.08% with the operating temperature at 573.15 K and carbon dioxide flow rate of 1 L/h were shown with 5 wt.% zeolite NaA.

Phase evolution, microstructure and dielectric properties of electrospun Ba(Zr0.2Ti0.8)O3–0.5(Ba0.7Ca0.3)TiO3

Ba(Zr0.2Ti0.8)O3–0.5(Ba0.7Ca0.3)TiO3 or simply BZT-0.5BCT has attracted increasing attention due to its excellent ferroelectric properties and lack of lead. BZT-0.5BCT nanofibers were fabricated by sol–gel assisted electrospinning and post-calcination process. Different types of analysis were utilized to study phase evolutions and characterization of calcined fibers. TGA indicated three stages of polymer decomposition at temperatures below 500 °C. FTIR spectroscopy revealed the presence of acetate salts of inorganic precursors in electrospun fibers. Also, it was determined that the formation of oxides started at temperatures around 300 °C and intensified with a rise in temperature. In keeping with DSC and FTIR results, XRD analysis revealed a low crystallization temperature of 550 °C for the perovskite phase. The room-temperature Raman spectroscopy demonstrated the coexistence of both orthorhombic and tetragonal phases at 900 °C and higher temperatures. SEM images illustrated the stability of fibrous morphology up to 1000 °C. High-temperature XRD showed that the curie temperature of nanofibers is between 120 and 150 °C. The dielectric constant of calcined fibers at 900 °C was measured to be 2283.

Effects of monomer composition on physical properties and enzymatic hydrolyzability of poly(butylene succinate‐co‐hexamethylene succinate)s

AbstractIn this study, various biodegradable materials, including poly(butylene succinate) (PBS), poly(hexamethylene succinate) (PHS), and poly(butylene succinate‐co‐hexamethylene succinate)s (P[BS‐co‐HS]s) containing different hexamethylene succinate (HS) contents, were prepared. The compositions, thermal properties, mechanical properties, hydrophilicity, and enzymatic hydrolyzability of the materials were investigated by various techniques. The results showed that the composition of the copolyesters was similar to the feeding ratio of the reactants. The melting and crystallization temperatures, thermal stability, and degree of crystallinity of the copolyesters decreased for low HS content and increased for high HS content. P(BS‐co‐HS)s containing 52 mol% HS exhibited low crystallization temperature (Tc), melting temperature (Tm), degree of crystallinity (Xc), and high hydrophilicity, elongation at break and enzymatic hydrolyzability. We also observed that low degree of crystallinity and high crystal defects, hydrophilicity, and high elongation at break could improve the enzymatic hydrolyzability of the materials.

Enhanced Interfacial Adhesion of Polydimethylsiloxane (PDMS) by Control of the Crosslink Density.

In this paper, we report a simple, fast, and one-step approach to improve the adhesion force of polydimethylsiloxane (PDMS) by incorporating inorganic nanoparticles that can control the physical, mechanical, and adhesion properties of the PDMS. An organic/inorganic PDMS-based composite was fabricated by the hydrosilylation of vinyl-decorated silica nanoparticles (v-SNPs) and the PDMS. The v-SNP/PDMS composite showed a significantly decreased elastic modulus and increased elongation compared with that of pristine SNPs incorporated with the PDMS composite (SNP/PDMS) and pristine PDMS. Furthermore, the v-SNP/PDMS composite exhibited a low glass-transition temperature and sharp crystallization and melting peaks in the differential scanning calorimetry curve compared with those of pristine PDMS and the SNP/PDMS composite. Moreover, the v-SNP/PDMS composite showed a high swelling ratio and crosslinked molecular weight and low gel fraction. These results may originate from the suppression of the PDMS-curing networks as the addition of the v-SNPs creates a low curing density because of the chemical bonding between PDMS and the v-SNPs. Finally, the v-SNP/PDMS composite showed an improvement of ~426% in the adhesion force compared with pristine PDMS and the SNP/PDMS composite. We anticipate that this v-SNP/PDMS composite could be used as a highly adhesive and hydrophobic coating material for various applications in industry.

Genesis of the Late Archean granitoids of the northern part of the Dharwar foreland (Dharwar Craton), south India – Insights from field, crystal size distribution, thermobarometry, microgeochemical and bulk-rock geochemical studies

An intrusive granitoid pluton into TTG-Dharwar Supergroup greenstone sequence is being reported for the first time from the Dharwar Foreland region. Based on field and petrographic characteristics, these granitoids are classified as - quartz-monzodiorites and granites. Occasional mafic bodies of dioritic-granodioritic composition with size ranging from small microgranular magmatic enclaves to bodies of several centimeters are common in these granitoids.The granitoids are devoid of any crystal-plastic fabric as well as high-strain characteristics. The textural (CSD) studies indicate that the quartz-monzodiorites are derived from magma mixing whereas the granites are derived from equilibrium crystallization of the magma derived from the reworking of quartz-monzodiorites. The P-T estimates indicate that the quartz-monzodiorites were crystallized at higher temperature (>950 °C) and pressure (3.09–4.36 kbar) conditions in a reducing environment at mid-crustal levels. However, the granites indicate lower temperature (<750 °C) and pressure (0.89–1.88 kbar) conditions of crystallization in an oxidizing environment at shallow-crustal levels. The bulk rock chemical characteristics indicate that the quartz-monzodiorites were derived from the melt generated by the mixing of two melts - a melt derived from the differentiation of sanukitoids senso lato (s.l.) and a melt derived from the partial melting of TTG. On the other hand, reworking of the hot crystallizing quartz-monzodiorite due to its rapid upliftment to shallow crustal levels resulted in a decompression melting which gave rise to granitic melts.The relative age of the Dharwad granitoids is estimated to be ∼2580–2560 Ma and unlike the other older granitoids (> 2.61 Ga) reported from the northern part of the Shimoga greenstone belt, the studied granitoids marks the final stage of cratonization in the Foreland region.

The Effect of Low-Temperature Crystallization of Fish Oil on the Chemical Composition, Fatty Acid Profile, and Functional Properties of Cow's Milk.

Simple SummaryNowadays, both consumers and producers are paying increasing attention to the health-promoting properties of food (functional food). Wide and multi-directional pro-healthy effects are shown by long-chain unsaturated omega-3 fatty acids (mainly eicosapentaenoic (EPA), and docosahexaenoic (DHA) ones) and conjugated linoleic acid dienes (CLA). On the other hand, saturated fatty acids (SFAs), particularly medium-chain ones, have adverse atherogenic and thrombogenic effects. The supplementation of dairy cows’ rations with fish oil subjected to low-temperature crystallization (LTC-FO) enriched with long-chain polyunsaturated fatty acids reduced milk fat yield and concentration and profitably modified the fatty acid profile. The level of SFAs, especially short- and medium-chain ones, in milk fat decreased. In turn, the content of polyunsaturated fatty acids (PUFAs), including biologically active ones like eicosapentaenoic (EPA), docosahexaenoic (DHA), CLA, and trans-vaccenic acid (TVA), increased. In conclusion, LTC-FO could be used to modify the nutritional and health value of milk.The study aimed to investigate the effect of supplementation of fish oil after the process of low-temperature crystallization (LTC-FO) enriched with long-chain polyunsaturated fatty acids (LC-PUFAs) on cow milk parameters. The experiment was carried out on 24 Polish Holstein Friesian cows. For 4 weeks, experimental (EXP) group animals (n = 12) were fed LTC-FO (1% of dry matter). Milk was collected two times: on days 14 and 30. LTC-FO supplementation decreased milk fat yield and concentration (p < 0.01). Higher levels of polyunsaturated fatty acids (PUFAs), including these with beneficial biological properties, i.e., eicosapentaenoic (EPA), docosahexaenoic (DHA), docosapentaenoic (DPA), CLA, alpha-linolenic acid (ALA), and TVA (p < 0.01), and lower levels of SFAs, especially short- (p < 0.01) and medium-chain ones (p < 0.05, p < 0.01), were found in the EXP group. The addition of LTC-FO reduced the value of atherogenic and thrombogenic indices as well as SFA/UFA and n-6/n-3 ratios and increased the content of n-3 PUFA and functional fatty acids (p < 0.01). The addition of LTC-FO also increased the delta-9 desaturase index for CLA/TVA and decreased it for pairs C14:1/C14:0 and C16:1/C16:0 (p < 0.05, p < 0.01).

Molecular design effects of alkoxide-derived precursor solution on low-temperature crystallization of cubic garnet type Li ion conductor

Cubic garnet-type Li ion conductor such as Li7La3Zr1.75Ta0.25O12 (c-LLZTO) are promising materials to develop all-solid-ceramic type Li ion batteries. For this study, we prepared c-LLZTO through the metal alkoxide route with chemical modification. Results show that chemical modification using acetic acid and distilled water for the partial hydrolysis lowered the crystallization temperature of the c-LLZTO with mono-phase at 973 K under ambient atmosphere. The obtained c-LLZTO with 63 nm crystallite size was sintered at 1373 K for 3 h to obtain a dense c-LLZTO pellet. The Li ion conductivity of the sintered c-LLZTO pellet exhibited higher ion conductivity of 3.48 × 10-4 Scm−1 at 300 K than those of the reported chemical-solution-derived cubic garnet-type Li ion conductors.

Wake‐Up Mechanisms in Ferroelectric Lanthanum‐Doped Hf0.5Zr0.5O2 Thin Films

Since the discovery of ferroelectricity in thin doped hafnium oxide layers, there is a rapidly growing interest in the implementation of this material into nonvolatile memory devices such as ferroelectric capacitors, transistors, or tunnel junctions. In most cases, a field‐cycling‐induced change in the remanent polarization is attributed to wake‐up and fatigue in ferroelectric HfO2 devices. The lanthanum‐doped hafnium/zirconium mixed oxide system is of broad interest due to its high endurance stability and low crystallization temperature which is necessary for low thermal budget, back‐end of line devices. Herein, a detailed temperature‐dependent field‐cycling study is performed in a wide temperature range from liquid nitrogen to room temperature to separate field‐cycling‐induced charge movements from phase change effects. Results are expected to be relevant for similar doped HfO2 ferroelectric layers.

Intermediate-phase-assisted low-temperature formation of \u03b3-CsPbI3 films for high-efficiency deep-red light-emitting devices

Black phase CsPbI3 is attractive for optoelectronic devices, while usually it has a high formation energy and requires an annealing temperature of above 300 °C. The formation energy can be significantly reduced by adding HI in the precursor. However, the resulting films are not suitable for light-emitting applications due to the high trap densities and low photoluminescence quantum efficiencies, and the low temperature formation mechanism is not well understood yet. Here, we demonstrate a general approach for deposition of γ-CsPbI3 films at 100 °C with high photoluminescence quantum efficiencies by adding organic ammonium cations, and the resulting light-emitting diode exhibits an external quantum efficiency of 10.4% with suppressed efficiency roll-off. We reveal that the low-temperature crystallization process is due to the formation of low-dimensional intermediate states, and followed by interionic exchange. This work provides perspectives to tune phase transition pathway at low temperature for CsPbI3 device applications.

Fabrication and crystallization behavior of hollow poly( l ‐lactic acid) nanofibers

In this study, a bundle of poly(l-lactic acid) (PLLA) hollow nanofibers was prepared through anodic aluminum oxide (AAO) membrane wetting method. The infiltrated PLLA in the nanopores of AAO membrane were isolated via etching of the membrane using phosphoric acid, preserving their original nanostructure. The outer diameter of isolated PLLA nanofibers and wall thickness were found to be 235 ± 17 nm and 38.5 ± 9 nm, respectively. The differential scanning calorimetry analysis showed that the hollow PLLA nanofibers exhibited lower melting and crystallization temperatures than the bulk PLLA sample. Furthermore, the wide-angle X-ray diffraction measurement suggested that PLLA crystallized preferentially along the 110/200 plane direction due to confinement effect of the AAO walls. Such hollow PLLA nanofibers may have potential application as a drug delivery system.

Assessment of magmatic fertility using pXRF on altered rocks from the Ordovician Macquarie Arc, New South Wales

This research presents a new method for assessing magmatic fertility using the portable X-ray fluorescence spectrometer (pXRF) in altered rocks from porphyry terranes. A study of Northparkes and global Cu--Au porphyries highlighted low Zr and Y trends associated with mineralising intrusions. Zircon saturation occurs at low Zr concentrations owing to low-temperature crystallisation depressed by high dissolved H2O in the melt. Yttrium depletion indicates hydrous magmatic conditions that cause hornblende to crystallise early. Previously geochemical differentiation of hydrous, potentially ore-forming (fertile) porphyries has relied on ratios of Sr/Y and Sr/MnO from geochemical and/or pXRF analysis of least altered rocks. Strontium is highly mobile and limits its use in altered terranes. Finding samples in porphyry terranes where Sr can be demonstrated to be retained is difficult given the ubiquity of alteration associated with porphyry emplacement. This precludes the widespread use of pXRF, as quantitative assessment of alteration is beyond the capabilities of pXRF technology. Using immobile elements overcomes issues with alteration and provides more reliable indicators of magmatic fertility. Using a systematic pXRF workflow, plots of Zr vs Y and Zr*Y vs Al2O3/TiO2 were successful in identifying 100% of the mineralising intrusions in the Northparkes intrusive complex and provide an indication of magmatic fertility and a proxy for melt hydration state. The ratios of Zr/Nb vs Y/Nb are insensitive to alteration including weathering and are indicative of evolution and dissolved H2O content of magmatic sources. Moving from bivariate plots to ratio plots shifts the data into a real-number space and provides a linear function to assess against magmatic fertility. Application of the fertility indicators to a regional dataset from New South Wales highlights areas of known porphyry mineralisation indicating that the method has the potential to be a useful indicator of fertility beyond the scope of the pilot study. KEY POINTS The fertility of porphyry intrusions is directly related to their dissolved H2O content and oxidation state. High dissolved H2O content in magmas causes early crystallisation of hornblende, and temperature depression. As a result Zr saturation occurs at low Zr concentrations that results in depletion of Y and the MREE in hydrous rocks compared with normal arc rocks. Magmatic fertility can be rapidly and cheaply assessed in the field using Zr and Y concentrations from pXRF analyses. The use of immobile elements facilitates magmatic fertility assessment in altered rock, which was previously impossible owing to the use of mobile elements Sr and MnO.

Effect of gold layer thickness on the low-temperature crystallization process of germanium thin films by gold-induced crystallization

The effect of Au layer thickness (1, 2.5, 5, 7.5 and 10 nm) on the low-temperature crystallization of Ge thin films (30 nm) was examined. It is found that the best Ge crystallinity is achieved at an Au layer thickness of 2.5 nm. This finding will open up the possibility to reduce the amount of Au consumption in the low-temperature crystallization process of Ge thin films.

Study of Low Temperature Preparation of Al Doped ZnO Powder and its Photocatalytic Properties

Aluminum doped ZnO crystal powders have been successfully prepared by sol-gel method with low temperature (150°C) crystallization process. The AlNO3 as material dopant were varied by 0.5 wt% and 1.0 wt% relate to 5 mmol of zinc acetate dihydrate as precursor. Degradation of the methylene blue (MB) was used to evaluate the photocatalytic property. The results showed that all ZnO samples have spherical morphology with hexagonal wurtzite crystal structures. The ZnO powder with 0.5 wt % of aluminum has a better photocatalytic property that related to the optical characteristics. The optimum of Al content (0.5wt%) reduces the crystallite size and give some advantages in optical characteristics that directly relate to the increments in photocatalytic behavior. The photodegradation rate of Al doped ZnO 0.5 wt% is increase almost 100% compared with ZnO undoped. The stability and reusability of 0.5 wt% Al doped ZnO as photocatalyst, is also observed by monitoring the photocatalytic behavior under 14 hours irradiation (in three recycle used)