Doped Crystals Research Articles

Progress in the Application of PtCo Alloy Catalysts in Oxygen Reduction Reactions for Fuel Cells

Proton Exchange Membrane Fuel Cells (PEMFCs) are considered an effective way to address energy shortages and environmental pollution due to their high efficiency, low-temperature operation, and environmental friendliness. However, the oxygen reduction reaction (ORR) at the cathode in PEMFCs is very slow and needs rare and expensive Pt-based catalysts, which limits their commercialization process. To reduce costs while maintaining efficient catalytic performance, researchers have developed various technological strategies, among which PtCo alloy catalysts have garnered widespread attention due to their excellent ORR catalytic performance. This article reviews the latest progress and current status of PtCo alloy catalysts in PEMFC oxygen reduction catalysis, discusses the impact of catalyst component control, particle size regulation, crystal face regulation, doping, and other regulatory strategies on the catalytic activity of fuel cells, and provides a detailed introduction to the most promising PtCo alloy structures, such as polyhedra, core-shell, nanoframes, and ordered intermetallic structures. At the same time, the research on catalyst supports is discussed, and the challenges and future prospects of PtCo alloy catalysts in their applications are pointed out.

Impact of Side Chain Chemical Structure on Doping and Thermoelectric Properties of Oriented PBTTT Thin Films

AbstractIn this contribution, doping of oriented thin films is investigated for three PBTTT polymers bearing different side chains including linear alkyl ─(CH2)12─H, single ether ─(CH2)7─O─(CH2)4─H and alkyl‐siloxane ─(CH2)5─(Si(CH3)2O)2─Si(CH3)3 A combination of transmission electron microscopy, polarized UV–vis–NIR spectroscopy and transport measurements helps uncover the essential role of the chemical nature of side chains on the efficacy of the doping and on the resulting thermoelectric performances in oriented PBTTT films. Siloxane side chains help to reach record alignment level of PBTTT with dichroic ratio beyond 50 for an optimized rubbing temperature but they impede effective doping of PBTTT crystals with F6TCNNQ, resulting in very poor TE properties. By contrast, doping the amorphous phase of all three PBTTTs with magic blue (MB) results in excellent TE performances. Both, chemical nature of side chains and semi‐crystalline structure of the polymer determine the efficacy of doping. The use of siloxane side chains further impacts the scaling laws S ∝ σ−1/s between the Seebeck coefficient S and the charge conductivity σ. An unexpected s = 2 exponent is observed and tentatively attributed to the dimensionality of charge transport in the highly oriented mesophase of PBTTT.

Multifunctional Sm3+ modified layered perovskite La2Ti2O7 single crystals: Enhanced piezoelectric performance and color-stable orange emission

The demand for multifunctional materials with optical and electrical properties in industrial high-temperature applications has witnessed a rapid upsurge. Among ultra-high Curie temperature perovskite-like layered structure piezoelectrics, La2Ti2O7 (LTO) single crystal possesses the highest piezoelectric coefficient, but the lack of luminescence limits its optical applications. In this work, by combining experiments and first-principles calculations, we find that Sm3+ doped LTO single crystals not only create strong orange emission with high-color-purity and high-color-stability under high temperature/pressure, but also achieve higher piezoelectric coefficient of 21.7 pC/N at 298 K and 25.6 pC/N at 773 K, accompanied by polarization enhancement originating from inner TiO6 octahedral twisting. In addition, systematic high-temperature in situ electrical measurements showed that Sm3+ doping also contributes to weakening the adverse effects of ferroelectric–ferroelectric phase transition on piezoelectricity, dielectricity, and conductivity. Our work provides insights into the performance optimization mechanisms of ultra-high Curie temperature piezoelectrics and paves the way for the development of high-performance electro-optic integrated and coupled devices for applications under extreme conditions.

Ultrahigh piezoelectric properties and high transparency relaxor ferroelectric single crystals obtained by the combination of rare-earth doping and AC-poling

High-performance relaxor ferroelectric single crystals, such as Pb(Mg1/3Nb2/3)O3–PbTiO3 (PMN–PT), play a crucial role in the applications of medical ultrasonic imaging due to their high piezoelectric properties. In this study, we successfully grew a 2-in. Eu-doped PMN–PT single crystal whose composition variation and electrical properties were systematically investigated. It was found that the PT content of the crystal boule increased gradually along the growth direction, while the change of Eu3+ content was opposite. The property results show that Eu-doped PMN–PT single crystals exhibit a remarkable piezoelectric coefficient of 3300 pC N−1 at DC-poling while maintaining the rhombohedral phase to a tetragonal phase transition temperature (TRT) at 88 °C and the coercive field (EC) at 2.7 kV cm−1, higher to the undoped single crystals. Through the study of the local structure of Eu-PMN–PT, it illustrated that the introduction of Eu3+ increased the standard deviation of an A sublattice from 3.0% to 4.8%. The dopant simultaneously enhanced a tetragonal phase ratio and local structural heterogeneity, resulting in improved piezoelectric properties and temperature stability of the crystal. We further treated the doped crystals with AC-poling to obtain ultrahigh piezoelectric performance (d33 > 4000 pC N−1) and high transparency. This work provides a new approach to achieve a relaxor ferroelectric single crystal with high performance and transparency with good temperature stability, which could be the material of choice for optoelectronic devices in the future.

(Invited) Photoluminescence and Scintillation Properties of Heavy Single Crystal Scintillators for X- and Gamma-Ray Detection

Scintillators are one of the luminescent materials, and have a function to convert a quantum of ionizing radiation to thousands of low energy photons immediately via interactions between the material and ionizing radiation [1,2]. Generally, scintillators are combined with photodetectors, and when the scintillation photons are emitted from the scintillator, photodetectors convert them to electrical signals. When the target ionizing radiation is high energy photons such as X- and gamma-rays, heavy materials are preferable for scintillators since the detection efficiency against high energy photons depends on density and effective atomic number. Up to now, many types of materials have been examined for scintillators, such as single crystals, glasses, and opaque and transparent ceramics [2]. Among them, bulk single crystalline scintillators have been applied for scintillation detectors owing to a superior optical quality including high transmittance and luminescence efficiency.In the conference, some recent results of development of heavy scintillators mainly containing Lu, Hf, Ta and Tl are introduced. These materials were synthesized by some single crystal growth techniques such as the floating zone and bridgman method. After the synthesis, they were examined on optical (photoluminescence excitation and emission spectra and decay curve) and scintillation (scintillation emission spectrum, decay curve, afterglow and pulse height) properties. In Lu-based crystals, rare earth doped Lu2O3 crystals are introduced, and especially, Tb- and Eu-doped ones show a high scintillation light yield. In Hf-based ones, some results of rare earth doped AEHfO3 (AE = alkali earth) crystals are presented, and Ce-doped (Mg,Ca)HfO3 shows a high scintillation light yield [3]. Among Ta-based crystals, Mg4(Nb,Ta)2O9 crystals have a high light yield due to charge transfer luminescence of Ta/Nb and O [4]. In Tl-based crystalline compounds, TlMgCl3 shows a high light yield and energy resolution [5]. In the conference, these results will be introduced.

Optical properties of Gd3+ doped bismuth silicate crystals based on first principles

Bismuth silicate (Bi4Si3O12, BSO) crystal, as a nonlinear optical material with excellent optical properties, has a wide range of applications in laser technology, optical communication, and optical information processing. In order to further improve its performance, this study adopts a first principles calculation method based on density functional theory (DFT), selects Gd3+ as the dopant, and calculates and explores the changes in optical properties of BSO crystals after doping with 1/12, 1/6, and 1/3Gd3+. The calculation results show that the doping of Gd3+ changes the electronic structure of BSO crystals, which is manifested in the emergence of new light absorption and emission characteristics, an increase in carrier concentration, an improvement in conductivity, and an enhancement of crystal polarization ability in optical properties. In addition, doping with Gd3+ increases the light transmission rate and reduces energy loss of BSO crystals, while releasing more energy during electron band transitions, effectively improving the luminescence performance of BSO crystals. The theoretical research in this article provides an important theoretical basis for understanding the influence of Gd3+ doping on the optical properties of BSO, and by optimizing the ratio of Gd3+, the optical properties of BSO can be further regulated, opening up new possibilities for its application in optoelectronic devices.

Cu(II) Stability and UV-Induced Electron Transfer in a Metal-Organic Hybrid: An EPR, DFT, and Crystallographic Characterization of Copper-Doped Zinc Creatininium Sulfate.

Single-crystal X-ray diffraction and electron paramagnetic resonance (EPR) spectroscopic experiments, complemented by quantum chemical DFT calculations, were carried out on the copper-doped metal-organic hybrid and Tutton salt analogue zinc creatininium sulfate to determine its crystal structure, to characterize the electronic structure of the doped Cu(II) binding site, and to propose a pathway for an excited-state, proton-coupled electron transfer (PCET) process in UV-exposed crystals. The crystal structure is isomorphous to that of cadmium creatininium sulfate, which has the transition ion, not in direct coordination with the creatinine, but forming a hexahydrate complex, which is bridged to a creatininium through an intervening sulfate ion. The EPR g (2.446, 2.112, 2.082) and copper hyperfine (ACu: -327, -59.6, 10.8 MHz) tensor parameters are consistent with doped copper replacing host zinc in the metal-hexahydrate complex. These parameters are similar to those observed for copper hexahydrate in doped Tutton salt systems at low temperature, where the unpaired electron occupies mainly the copper 3dx2-y2 orbital. At room temperature in the Tutton systems, vibration couplings stemming from a dynamic Jahn-Teller effect cause tensor averaging which results in a reduction in their maximum g-tensor and hyperfine tensor values. However, like for the doped isomorphous Cd creatinine crystal, the Cu(II) EPR exhibits little, or no room temperature averaging compared to its low temperature pattern. Samples exposed to 254 nm UV light generate a carbon-centered free radical species, characterized by an isotropic g-tensor (g = 2.0029) and an alpha-proton hyperfine coupling (-24 -14 +4 G). These parameters identify it as a creatinine radical cation formed by the oxidative release of one of its C2 methylene hydrogens. DFT calculations confirm the unpaired electronic structures of both the Cu(II) site and free radical. The growth in radical concentration with an increase in the UV exposure time coincides with a decrease in the copper EPR signal, indicating a coupled light-induced oxidation reduction process. A comparison of the crystal structure with the EPR parameters and DFT results provides evidence for a UV-induced PCET.

Effect of Different Doping Concentrations on the Properties of Fe2+:ZnSe and Fe2+, Cr2+:ZnSe Crystals Grown by the Chemical Vapor Transport Method.

The Fe2+:ZnSe crystal is an important material for 3-5 μm mid-infrared lasers. In this work, we have grown different doping concentrations of Fe2+:ZnSe and Fe2+, Cr2+:ZnSe by the chemical vapor transport method. The doped crystals have the same structure. The lattice constant increases slightly with a higher Fe2+ concentration, while the doped Cr2+ has a great influence on the lattice constant. Besides, with a higher Fe2+ concentration, the TO mode has no change and the LO mode presents a small blue shift. The doped ZnSe crystals all have a wide absorption peak in the range of 2.3-4.5 μm, and these absorption peaks widen with the increase of the Fe2+ doping concentration. Besides, in the range of 5-20 μm, the crystals have good transparency. The concentrations of 3, 2, and 1% Fe2+ samples are calculated to be 4.15 × 1019, 3.27 × 1019, and 3.02 × 1019 cm-3, respectively, and the Fe2+ concentration of the Fe2+, Cr2+:ZnSe sample is 3.71 × 1019 cm-3. The band gap decreases from 2.52 to 2.27 eV with a higher Fe2+ doping concentration. Therefore, we can modulate the absorption bandwidth and band gap by doping the ion concentration, which is more suitable for developing mid-infrared gain medium applications.

Morphology and Luminescence Properties of Transition Metal Doped Zinc Selenide Crystals.

Zinc selenide is an excellent matrix material to dope with rare-earth and transition metal to achieve mid-infrared luminescence to develop high power lasers. The luminescence, morphology and refractive index is significantly affected by the doping and defects generated due to size and valency of dopants, concentration, growth process and convection during the growth. The aim of the study is to investigate effect of point and line defects generated due to low doping of iron and chromium on the emission and morphology of the zinc selenide. Luminescence and morphological properties of large iron and chromium doped zinc selenide single crystals were studied to evaluate the effect of extremely low residual impurities and defects associated with the doping process. The emission properties following both short wavelength (i.e., ultraviolet; 350-370nm) excitation and longer wavelength (i.e., near infrared; 850-870nm) excitation were characterized. Luminescence emission bands were identified in both doped crystals. In addition to the primary emission bands, satellite peaks and intra-center transitions were also observed. Due to local population defects associated with the residual impurities (ppm to ppb) in the Fe-ZnSe and Cr-ZnSe crystals, peak emission wavelengths were observed to shift. The emission bands were found to decrease in intensity due to recombination of residual impurity co-dopants and complex defects generated during growth and fabrication. Cryogenic temperature analyses revealed a very clean emission band due to freezing of some of the point and line defects. An emission band observed at 980nm for both crystals at room temperature as well as cryogenic temperatures indicates a vibronic peak in ZnSe. The scanning electron microscopy (SEM) images of the local morphology support the conclusion that small crystallites in doped crystals are also present.

Study on the optical properties of Sm3+ doped bismuth silicate crystals based on first principles

Abstract This study systematically investigated the effect of Sm3+ doping on the optical properties of bismuth silicate (Bi4Si3O12, abbreviated as BSO) crystals using first principles calculations based on density functional theory (DFT). By calculating the dielectric function, reflectivity, absorption coefficient, refractive index, conductivity, and energy loss function of BSO crystals under different Sm3+ doping ratios, we found that moderate Sm3+ doping can increase the dielectric function of BSO crystals, and the real part of the dielectric function represents the material’s ability to respond to the electric field, that is, the macroscopic polarization degree. Therefore, moderate Sm3+ doping enhances the polarization ability of BSO crystals. Simultaneously doping an appropriate amount can effectively enhance the conductivity and light (visible and infrared) absorption ability of BSO crystals, and reduce the energy loss between electrons in BSO crystals, thereby improving their luminescence performance. Specifically, when the Sm3+ doping ratio is 1/6, the optical properties of BSO crystals are significantly improved. These findings not only enhance the understanding of the mechanism of optical performance changes in rare earth ion doped BSO crystals, but also provide a theoretical basis for the development of new rare earth doped optical materials.

Visible Light-Sensitive Sustainable Quantum Dot Crystals of Co/Mg Doped Natural Hydroxyapatite Possessing Antimicrobial Activity and Biocompatibility.

Cutting-edge research in advanced materials is increasingly turning toward the development of novel multifunctional nanomaterials for use in high-tech applications. This research uses the solid-state method as a solvent-free technique to create multifunctional quantum dot (QD) hydroxyapatite (HA) crystals from bovine bone waste. By incorporating cobalt (Co) and magnesium (Mg) into the HA structure, the crystallinity of the hexagonal HA nanoparticles (99.7%), showing QD crystals is enhanced. Oxygen vacancies on the surfaces of the HA nanoparticles contributed to their bandgap falling within the visible light range. In addition, the dopants substituted calcium in the HA crystal structure and generated a divalent oxidation state, shifting the bandgap of natural HA toward red wavelengths (3.26 to 1.94eV). Moreover, the incorporation of Co led to magnetization within the HA structure through spin polarization. Additionally, the doped QD crystals of HA nanoparticles showed significant antimicrobial activity against Escherichia coli, Staphylococcus aureus, and bacteriophages MS2, particularly under visible light exposure. In short, the Co/Mg co-doped HA nanoparticles exhibited ferromagnetic properties, sensitivity to visible light, biocompatibility, and considerable antimicrobial effects, establishing their potential as sustainable multifunctional materials for biomedical applications, especially in anti-infection treatments.

Highly Efficient Red/Near‐Infrared Phosphorescence from Doped Crystals

AbstractOrganic red/near‐infrared (NIR) room temperature phosphorescence (RTP) materials with low toxicity and facile synthesis are highly sought after, particularly for applications in biotechnology and encryption. However, achieving efficient red/NIR RTP emitters has been challenging due to the weak spin‐orbit coupling of organics and the rapid nonradiative decay imposed by the energy gap law. Here we demonstrate highly efficient red/NIR RTP with boosted quantum yields (Φps) of up to 32.96 % through doping the thionated derivatives of phthalimide (PAI) (MTPAI and DTPAI) into PAI crystals. The red‐shifted photoluminescence (PL) stems from a combination of the external heavy atom effect and the formation of emissive clusters centered around electron‐rich sulfur atoms. Furthermore, the dopants enhance exciton generation efficiency and facilitate energy transfer from smaller PAI units to larger aggregates, leading to dramatically increased Φp. This strategy proves universal, opening possibilities for acquiring long‐wavelength RTP with tunable photophysical properties. The doped crystals exhibit promising applications in optical waveguides and encryption paper/ink. This research provides a practical approach to obtaining long‐wavelength RTP materials and offers valuable insights into the mechanisms governing host‐guest systems.

Highly Efficient Red/Near-Infrared Phosphorescence from Doped Crystals.

Organic red/near-infrared (NIR) room temperature phosphorescence (RTP) materials with low toxicity and facile synthesis are highly sought after, particularly for applications in biotechnology and encryption. However, achieving efficient red/NIR RTP emitters has been challenging due to the weak spin-orbit coupling of organics and the rapid nonradiative decay imposed by the energy gap law. Here we demonstrate highly efficient red/NIR RTP with boosted quantum yields (Φps) of up to 32.96 % through doping the thionated derivatives of phthalimide (PAI) (MTPAI and DTPAI) into PAI crystals. The red-shifted photoluminescence (PL) stems from a combination of the external heavy atom effect and the formation of emissive clusters centered around electron-rich sulfur atoms. Furthermore, the dopants enhance exciton generation efficiency and facilitate energy transfer from smaller PAI units to larger aggregates, leading to dramatically increased Φp. This strategy proves universal, opening possibilities for acquiring long-wavelength RTP with tunable photophysical properties. The doped crystals exhibit promising applications in optical waveguides and encryption paper/ink. This research provides a practical approach to obtaining long-wavelength RTP materials and offers valuable insights into the mechanisms governing host-guest systems.

Directional growth and composition design of the highly disordered Yb3+ doped Ca(Gd1-xLux)AlO4 crystals for ultrafast lasers

The unique disordered structure of the CaGdAlO4 crystal, combined with its exceptional thermal and spectral properties, has contributed to its growing popularity in the field of ultrafast lasers. In this work, high quality Yb3+ doped CaGdAlO4 crystals were directionally grown by the rapid and cost-effective micro-pulling down method for the first time. The anisotropic analysis determined [100]-orientation as the optimal growth direction due to its superior spectral, thermal and continuous-wave laser properties compared to that of [001]-orientation. Based on the optimized [100]-orientation, two novel crystals, Yb3+:CaGd1-xLuxAlO4 (x = 0.05 and 0.1), were designed by incorporating Lu3+ into Gd3+ site. Benefiting from the enhanced structure disorder induced by Lu3+ co-doping, the Yb3+:CaGd1-xLuxAlO4 crystals demonstrated superior spectral and pulsed laser performance compared to that of Yb3+:CaGdAlO4, featuring a broader emission spectrum, narrower pulse duration and higher peak power. The utilization of anisotropy and composition design strategies effectively enhanced the spectral and pulsed laser properties, providing a feasible way for the optimization of compact and high-performance laser devices.

Structural Modifications due to Bi-Doping in MAPbBr3 Single Crystals and Their Impact on Electronic Transport and Stability.

Doping strategy in lead halide perovskites is essential to enhance its optoelectrical properties and expand the potential applications. In this work, the mechanisms, for how dopants affect the overall structural, optical, electrical, and chemical properties and stability of lead halide perovskite materials, are investigated. This is done by specifically considering various bismuth (Bi)doping concentrations in MAPbBr3 single crystals grown using the inverse temperature crystallization method. The resultant doped single crystals exhibit a saturation point when Bi concentration exceeds 0.063% which is considered an optimum doping point. The highest thermal stability is also achieved at this doping concentration among the doped single crystals. This study clearly identifies how Bi doping affects the properties of MAPbBr3 and extends to consider stability, which has not been fully considered for MA-based perovskites previously. This will provide a clear understanding of evaluating doped perovskite materials for enhanced material properties, device performance, and stability.

Achieving Efficient X-ray Scintillation of Purely Organic Phosphorescent Materials by Chromophore Confinement.

Scintillators have attracted significant attention due to their wide-ranging applications in both industrial and medical fields. However, one of the ongoing challenges is the efficient utilization of triplet excitons to achieve high radioluminescence efficiency. Here, a series of purely organic phosphors is presented for X-ray scintillation, employing a combined rigid and flexible host-guest doping strategy. The doped crystals exhibit a remarkable maximum phosphorescence efficiency of 99.4% under UV excitation. Furthermore, upon X-ray irradiation, the radioluminescence intensities of the doped phosphors are markedly higher compared to their single-component crystal counterparts. Through systematic investigations, it is demonstrated the crucial role of confining isolated chromophores in enhancing scintillation efficiency. Additionally, a transparent scintillator screen fabricated with the doped phosphor exhibits excellent X-ray imaging performance, achieving a high spatial resolution of 18.0 lpmm-1. This work not only offers valuable insights into suppressing non-radiative transitions of triplet excitons during scintillation but also opens a new avenue for designing highly efficient purely organic phosphorescent scintillators.

Modification of the Spectral Absorption Characteristics of ZnGeP2 in the THz and IR Wavelength Ranges Due to Diffusion Doping with Impurity Atoms of Mg, Se, Sn, and Pb

This study demonstrates that diffusion doping of ZGP single crystals with impurity atoms (Mg, Se, Sn, Pb) leads to a decrease in the specific conductivity of the samples. Consequently, this results in reduced absorption in the terahertz frequency range (150–1000 μm). It has been shown that doping ZGP samples with selenium (Se) and lead (Pb) atoms reduces absorption in the infrared region from 0.3–0.6 cm−1 to 0.06–0.09 cm−1. Doping with tin (Sn) leads to a decrease in absorption only in the wavelength region near 2.1 μm from 0.2 cm−1 to 0.05 cm−1. The proposed mechanism for the decrease in infrared absorption is a reduction in zinc vacancies due to doping with impurity atoms. This research lays the groundwork for a technology that produces ZGP crystals with minimal absorption within the 2–8 μm wavelength range, eliminating the need for fast electron beam irradiation technology. This advancement will facilitate the fabrication of ZGP crystals with arbitrary apertures.

Analisis Interaksi Cahaya Dan Material Dalam Teknologi Fotovoltaik

Photovoltaic (PV) technology plays a key role in the transition towards renewable energy sources. The interaction of light with semiconductor materials is the main factor that determines energy conversion efficiency. This study analyzes the current literature on the interaction mechanisms of light with various types of photovoltaic materials, including silicon, perovskite, and organic materials. Research shows that optical properties, such as light absorption and scattering, have a significant effect on solar cell performance. In addition, factors such as crystal structure, morphology, and material doping also influence efficiency. These findings highlight the importance of innovation in material design and fabrication techniques to improve the efficiency of photovoltaic systems. Recommendations for further research are also discussed, especially in the development of new materials that can maximize light interactions.

Tunable Spectral Emission from 0D Rb3ZnBr5 Crystals for Single‐Component Multi‐Color LED Applications

AbstractThe development of efficient, stable, and cost‐effective luminescent materials is crucial for advancing lighting and display technologies. In this study, a series of tunable luminescent materials based on the novel 0D all‐inorganic perovskite (AIP) crystal Rb₃ZnBr₅ (RZB) is obtained. The emission of Sn2⁺ doped RZB spans the entire visible light range and extends into the near‐infrared (NIR) region, achieving a photoluminescence quantum yield (PLQY) of 75%. The distinct lifetimes combined with theoretical calculations, indicate that the broadband dual‐peak emissions at 496 and 636 nm originate from the singlet and triplet states of Sn2⁺, respectively, which is rarely observed in Sn2⁺‐doped perovskite crystals. The phosphor RZB:Sn2⁺ demonstrates the high thermal stability, along with excellent moisture and air stability. Co‐doping RZB with Sn2⁺ and Mn2⁺ broadens the excitation spectrum and allows precise control over the excitation wavelength, facilitating dynamic transitions from warm white to yellow and green light. This feature is particularly beneficial for multicolor LEDs and multi‐level anti‐counterfeiting applications.

Thermal conductivity in solid solutions of lithium niobate tantalate single crystals from 300 K up to 1300 K

Lithium niobate tantalate (LiNb1−xTaxO3, LNT) solid solutions offer exciting new possibilities for applications ranging from optics, piezotronics, and electronics beyond the capabilities of the widely used singular compounds of lithium niobate (LiNbO3, LN) or lithium tantalate (LiTaO3, LT). Crystal growth of homogeneous LNT single crystals by the Czochralski method is still challenging. One key aspect of homogeneous growth is the accurate knowledge of thermal conductivity through the crystal boule during the growth, which is central to control the crystal growth. Therefore, the temperature dependent thermal conductivity of pure LN, LT, and LNT solid solutions, as well as of selected doped LN and LT crystals (Mg, Zn) was investigated across the temperature range from 300 to 1300 K. The results that span across the whole composition range can directly be applied for optimizing growth conditions of both LNT solid solutions as well as doped and undoped LN and LT crystals.