Mixing In Nd Research Articles

δ-Bonding modulates the electronic structure of formally divalent nd1 rare earth arene complexes.

Landmark advances in rare earth (RE) chemistry have shown that divalent complexes can be isolated with non-Aufbau 4f n {5d/6s}1 electron configurations, facilitating remarkable bonding motifs and magnetic properties. We report a series of divalent bis-tethered arene complexes, [RE(NHAriPr6 )2] (2RE; RE = Sc, Y, La, Sm, Eu, Tm, Yb; NHAriPr6 = {N(H)C6H3-2,6-(C6H2-2,4,6-iPr3)2}). Fluid solution EPR spectroscopy gives g iso < 2.002 for 2Sc, 2Y, and 2La, consistent with formal nd1 configurations, calculations reveal metal-arene δ-bonding via mixing of nd(x 2-y 2) valence electrons into arene π* orbitals. Experimental and calculated EPR and UV-Vis-NIR spectroscopic properties for 2Y show that minor structural changes markedly alter the metal d(x 2-y 2) contribution to the SOMO. This contrasts 4f n {5d/6s}1 complexes where the valence d-based electron resides in a non-bonding orbital. Complexes 2Sm, 2Eu, 2Tm, and 2Yb contain highly-localised 4f n+1 ions with no appreciable metal-arene bonding by density functional calculations. These results show that the physicochemical properties of divalent rare earth arene complexes with both formal nd1 and 4f n+1 configurations are nuanced, may be controlled through ligand modification, and require a multi-pronged experimental and theoretical approach to fully rationalise.

The Montecristo mining district, northern Chile: the relationship between vein-like magnetite-(apatite) and iron oxide-copper–gold deposits

The Montecristo district, northern Chile, is one of the few places worldwide where there is a direct relationship between magnetite-(apatite) (MtAp) mineralization and iron oxide-copper–gold (IOCG) mineralization. The MtAp mineralization includes Ti-poor magnetite, fluorapatite, and actinolite and is crosscut and partially replaced by a younger IOCG mineralization that includes a second generation of actinolite and magnetite with quartz, chalcopyrite, pyrite, and molybdenite. The MtAp stage at Montecristo is interpreted as the crystallized iron-rich melts that used the pre-existing structures of the Atacama Fault System as conduits. These rocks later acted as a trap for hydrothermal IOCG mineralization. Geochronology data at Montecristo indicate that the host diorite (U–Pb zircon 153.3 ± 1.8 Ma, 2-sigma), MtAp mineralization (40Ar-39Ar in actinolite, 154 ± 2 Ma and 153 ± 4 Ma, 2-sigma), and the IOCG event (Re-Os on molybdenite, 151.8 ± 0.6 Ma, 2-sigma) are coeval within error and took place in a time span of less than 3.4 Ma. The εHfi and εNdi values of the host diorite are + 8.0 to + 9.8 and + 4.3 to + 5.4, respectively. The whole-rock 87Sr/86Sri values of the IOCG mineralization (0.70425 to 0.70442) are in the lower end of those of the MtAp mineralization (0.70426–0.70629). In contrast, εNdi values for the IOCG mineralization (+ 5.4 and + 5.7) fall between those of the MtAp rocks (+ 6.6 to + 7.2) and the host diorite, which suggests that the IOCG event was related to fluids having a more crustal Nd (εNdi < + 5.7) composition than the MtAp mineralization. This likely reflects the mixing of Nd from the MtAp protolith and a deep magmatic-hydrothermal source, very likely an unexposed intrusion equivalent to the host diorite. Sulfur isotope compositions (δ34S, + 0.3 to + 3.4‰) are consistent with a magmatic source.

Perspectives for the Brazilian Industry of Rare-Earth Magnets

The Brazilian reserves of rare earths were updated. Brazil is among the countries with the largest reserves of rare earths in the world. Rare earths present a series of applications in the high technology industry. Magnet production is one of the applications requesting largest volumes of rare earths. Another relevant application is catalysis and Petrobras needs 1000 tons/year of La2O3 for petroleum refining. CBMM mine has a pilot plant able to produce tons of separated rare earth oxides, notably didymium (a mixing of Nd and Pr oxides) used in magnet manufacture. Serra Verde mine in Goiás also produced separated rare earth oxides. The magnet production in Brazil can be important for the high efficiency electrical motors industry and also for the automotive industry.

Nonlinear mixing of Nd:YAG lasers; harmonic and sum frequency generation

Nonlinear optical materials give rise to a number of phenomena under high intensity of the incident electric field, with nonlinear mixing being a prominent example. This article discusses such nonlinear mixing processes of Nd:YAG lasers in BBO outside the more common harmonics of the 1.064 μm transition (0.532 μm, 0.366 μm and 0.266 μm). In particular, harmonics of the less common 0.946 μm transition (0.473 μm and 0.315 μm) as well as sum frequency of the 1.052 and 1.319 μm transitions (0.585 μm) and its second harmonic (0.293 μm) is discussed.

Optical phase conjugation by four-wave mixing in Nd:YAG laser oscillator for optical energy transfer to a remote target

A self-starting phase conjugator was designed for optical energy transfer to a remote target. Saturable-gain four-wave mixing in a laser resonator was achieved using a flash-lamp pumped Nd:YAG crystal and phase-conjugate light (PCL) generation were verified. Wavefront correction experimentation revealed that beam wander caused by air turbulence is compensated. Tracking capability was demonstrated in the range of 9 mrad with tracking accuracy of ±0.04 mrad. The maximum field of view was measured to be 4.7°. Dependence of phase-conjugate light energy on reference light energy was investigated. The maximum output of 320 mJ was obtained. The temporal behavior of PCL is discussed based on the four-wave mixing mechanism. Unlike a conventional loop resonator type phase conjugator, this system is applicable for wireless energy transfer to a remote target.

All-solid-state continuous wave doubly linear resonator sum-frequency mixing yellow laser

We report a continuous-wave (CW) yellow laser emission by sum-frequency mixing in Nd:YVO4 crystal. Using type-II critical phase-matching KTP crystal, a yellow laser at 593.5 nm is obtained by 1064 and 1342 nm intracavity sum-frequency mixing. The maximum laser output power of 2.1 W is obtained when an incident pump laser of 18.2 W is used. At the output power level of 2.1 W, the output stability is better than 3.2%.

Diode-pumped green light source based on intracavity sum frequency generation

We report a continuous-wave (CW) green laser emission by sum-frequency mixing in Nd:YVO4 and Nd:YLF crystals. Using type-II critical phase-matching (CPM) KTP crystal, a green laser at 539 nm is obtained by 914 and 1313 nm intracavity sum-frequency mixing. The maximum laser output power of 388 mW is obtained when an incident pump laser of 18.2 W is used. At the output power level of 388 mW, the output stability is better than 4.6%.

Diode laser pumped green light source based on intracavity sum frequency generation

We report a continuous-wave (CW) green laser emission by sum-frequency mixing in Nd:YVO4 and Nd:YLF crystals. Using type-II critical phase-matching (CPM) KTP crystal, a green laser at 539 nm is obtained by 914 and 1313 nm intracavity sum-frequency mixing. The maximum laser output power of 388 mW is obtained when an incident pump laser of 18.2 W is used. At the output power level of 388 mW, the output stability is better than 4.6%.

490-nm generation by sum-frequency mixing of diode pumped Nd:GdVO4-Nd:YLF lasers

We report a continuous-wave (CW) blue laser emission by sum-frequency mixing in Nd:GdVO4 and Nd:YLF crystals. Using type-I critical phase-matching (CPM) LBO crystal, a blue laser at 490 nm is obtained by 1063 and 908 nm intracavity sum-frequency mixing. The maximum laser output power of 118 mW is obtained when an incident pump laser of 18.2 W is used. At the output power level of 118 mW, the output stability is better than 4.2%.

Atomistic mechanism of cyclic phase transitions in Nd–Fe–B based intermetallics

Mechanical milling induced atomic disorder and the mechanism of the cyclic crystal → amorphous → crystal phase transitions in a Nd 2Fe 14B intermetallic – based Nd 10Fe 85B 5 alloy were investigated. Least square first shell fitting of Extended X-ray Absorption Fine-Structure (EXAFS) data of mechanically milled samples revealed that phase evolution during mechanical milling of Nd 10Fe 85B 5 alloy occurred in two stages as a result of two dynamical effects: milling induced forced atomic mixing and enhanced diffusion due to continuous production of point defects. In the first stage of milling, atomic mixing of Nd and Fe atoms dominated, resulting in extensive chemical and structural disorder in the initially ordered intermetallic, followed by amorphization. The second stage of milling was characterized by a remarkable increase in point defect density. Enhanced diffusion resulted in redistribution of alloy atoms and annihilation of these point defects leading to the precipitation of α-Fe nanocrystals in the amorphous matrix. Thus the time evolution of defect structures formed during mechanical milling and their atomic scale interactions led to the cyclic phase transitions in the Nd 10Fe 85B 5 alloy. These milling induced changes in atomic order were found to strongly influence magnetic properties. Crystallization of mechanically milled alloy and effect of annealing parameters on magnetic properties was also analyzed.

Diode-Pumped Nd:CNGG-LBO CW sum-frequency mixing blue-green laser at 497 nm

We report for the first time a continuous-wave (CW) blue-green laser emission by sum-frequency mixing in Nd:CNGG crystal. Using type-I critical phase-matching LBO crystal, a blue-green laser at 497 nm is obtained by 1061 and 935 nm intracavity sum-frequency mixing. The maximum laser output power of 232 mW is obtained when an incident pump laser of 18.2 W is used. At the output power level of 232 mW, the output stability is better than 3.67%. The beam quality M 2 value is are about 1.26 and 1.38 in both horizontal and vertical dimensions respectively.

All-solid-state Nd:YAG-LBO yellow laser at 572 nm

We report for the first time a continuous-wave (CW) yellow laser emission by sum-frequency mixing in Nd:YAG crystal. Using type-I critical phase-matching LBO crystal, a yellow laser at 572 nm is obtained by 1444 and 946 nm intracavity sum-frequency mixing. The maximum laser output power of 178 mW is obtained when an incident pump laser of 18.2 W is used. At the output power level of 178 mW, the output stability is better than 4.2%.

Intracavity sum-frequency generation of CW blue light in Nd:LuVO4 laser

We report for the first time a continuous-wave (CW) blue laser emission by sum-frequency mixing in Nd:LuVO4 crystal. Using type-I critical phase-matching (CPM) LBO crystal, a blue laser at 493 nm is obtained by 1066 and 916 nm intracavity sum-frequency mixing. The maximum laser output power of 520 mW is obtained when an incident pump laser of 18.2 W is used. At the output power level of 520 mW, the output stability is better than 2.8%. The beam quality M2 value is are about 1.22 and 1.31 in both horizontal and vertical dimensions respectively.

3.62 W of continuous-wave orange-yellow light generated by intra-cavity sum-frequency mixing of Nd:YVO 4

A design of laser-diode array (LDA) end-pumped Nd:YVO 4 laser that generates simultaneous laser action at wavelengths 1064 and 1342 nm is presented. Using type-I critical phase matching (CPM) BiB 3O 6, 593.5 nm continuous-wave (cw) Orange-yellow laser is obtained by 1064 nm and 1342 nm in an intra-cavity sum-frequency mixing. The maximum laser output power of 3.62 W is obtained when an incident pump laser of 27.5 W is used. The optical-to-optical conversion is up to 13.2%. To the best of our knowledge, this is the highest conversion efficiency at 593.5 nm in an intra-cavity sum-frequency Nd:YVO 4 laser.

First-Principles Thermochemistry and Thermodynamic Modeling of the Al2O3-Nd2O3-SiO2-Y2O3 Pseudoquaternary System

The Al2O3–Nd2O3–SiO2–Y2O3 pseudoquaternary system was thermodynamically modeled with a focus on the phase equilibria concerning the sintering of neodymium-doped yttrium aluminum garnet, Nd:YAG ((Y1−xNdx)3Al5O12). The Nd2O3–SiO2 and Nd2O3–Y2O3 systems were evaluated. Due to the lack of experimental thermochemical data, first-principles calculations were used to predict the enthalpy of formation of Nd2SiO5 and the enthalpy of mixing of Nd in YAG. Isothermal sections of the Al2O3–Nd2O3–SiO2, Al2O3–Nd2O3–Y2O3, and Nd2O3–SiO2–Y2O3 pseudoternary systems are presented.

Use of Nanodiamonds as a Reducing Agent in a Chlorate‐based Energetic Composition

AbstractTo our knowledge, the incorporation of nanodiamond (nD) as a reducing agent in an energetic composition has never been reported in the literature. Diamond exhibits particularly interesting physico‐chemical properties: high density, good energetic potential, and relatively low thermal sensitivity. This study proposes to demonstrate that an explosive energetic composition can be obtained by physical mixing of nD and potassium chlorate (PC). First, the energetic characteristics of this formulation were compared to those of the famous “white powder” made of PC and saccharose and discovered by the French chemist Berthollet in the 18th century. In the second part, the combustion of pelletized nD‐based mixtures initiated by a laser beam was studied by time resolved cinematography. The deflagration velocity was measured on the most energetic composition, which has a slightly negative oxygen balance (OB=−30.1%).

Optimum conditions for ultraviolet-laser generation based on self-frequency sum mixing in Nd^3+-activated borate crystals

A simple theoretical model of the ultraviolet laser radiation generated by self-frequency sum mixing in a single argon-pumped Nd3+-doped nonlinear crystal is proposed. Self-absorption by both absorption edge and Nd3+ bands lying in the ultraviolet range is taken into account. The model is then applied to Nd3+:YAl3(BO3)4,Nd3+:GdCa4O(BO3)3, and Nd3+:YCa4O(BO3)3 borate laser crystals. The crystal length, pump wavelength, and Nd3 concentration that optimize the pump to ultraviolet efficiency are determined for each case. The ultraviolet output power is found to be tens of milliwatts for a pump power of 2 W.

Self-frequency-sum mixing in Nd doped nonlinear crystals for laser generation in the three fundamental colours: The NYAB case

When combined with a suitable nonlinear crystal host, several coincidences occurring in Nd 3+ ions allow for simultaneous generation of laser radiation in the three fundamental colours; red, green and blue (RGB) in the same solid state laser crystal. We show experimentally this possibility in neodymium doped yttrium aluminium borate (NYAB) Nd 3+:YAl 3(BO 3) 4, although the same achievement is very likely to be possible in other nonlinear crystals containing Nd 3+ laser active ions.

Effects of ‘random deformations’ in the EPR spectra of Jahn–Teller Cu(D 2O) 6 complexes in the mixed KND 4Zn(SO 4) 2[rad]6D 2O Tutton salt

The EPR study of high quality mixed crystal K(ND 4)Zn(SO 4) 2 6D 2O shows that the doped 63Cu(D 2O) 6 complexes exist simultaneously in two configurations, differing by the directions of Jahn–Teller spontaneous deformation. This observation directly confirms the early supposition that the elongation direction of the doped copper complexes is determined by the indirectly interacting monovalent cations. The high temperature EPR spectra have a ‘powder-like’ appearance and, at lower temperatures, a significant deformation of the resonant lines is observed. These effects are explained as a result of random deformations, introduced by the mixing of ND 4 + and K + ions on the electronic structure and dynamics of the Jahn–Teller hexaaqua copper complexes. Internal deformations change the complex rhombicity and parameters of the Jahn–Teller adiabatic potential leading to their random spread. It is shown that in a low symmetry case, the statistic, symmetrical distributions of these parameters may lead to the asymmetric distribution of g- and A-values, resulting in the asymmetric distribution of the EPR resonant fields. The proposed approach is confirmed by the presentation of theoretical spectra calculated for the assumptions of randomly distributed EPR spectra parameters. These spectra reproduce well experimentally observed spectra in K(ND 4)Zn(SO 4) 2 6D 2O crystals.

Widely tunable deep ultraviolet generation in CLBO

In a single cut cesium lithium borate (CsLiB 6O 10 or CLBO) crystal we have generate deep UV radiation tunable from 195 to 265 nm (with a gap from 210 to 226 nm due to crystal cut limitation). Radiation in the 195–210 nm region is generated by noncollinear sum-frequency mixing of Nd:YAG laser radiation with the second harmonic (239–262 nm) of the dye laser radiation. However, radiation in the region of 210–237.5 nm and 236.8–265 nm is generated by third harmonic and second harmonic generation of the dye laser, respectively. All three interactions for coverage of the said range are made in the same cut CLBO crystal Type-I, θ=80° and ϕ=45°. The shorter wavelength tuning is phase-matching limited. A conversion efficiency of 14% is realised in our 5.5 mm long crystal for the generation of 241.7 nm radiation by Type-I second harmonic generation with a fundamental input beam intensity as low as 14.6 MW/cm 2.