Conductivity Of Nd Research Articles

Thermal distortions in high-power end-pumped Nd:YVO4 crystals

A high-resolution infrared thermal imager is employed to measure temperature and fit the thermal conductivity of Nd:YVO4 crystal. A theoretical model to analyze the thermal distortion of end-pumped Nd:YVO4 crystals is established. Both simulations and experiments reveal that with high-power pumping, the thermal effects of Nd:YVO4 crystal cause spherical aberration as well as astigmatism. It is identified that the major cause of astigmatism is the anisotropy of the Nd:YVO4 crystals’ thermal conductivity. The influence of astigmatism on the ellipticity of the output beam is investigated, and the significance of astigmatism compensation is demonstrated. The experimental results agree well with the simulation results.

Structure and conductivity of Nd6MoO12-based potential electron–proton conductors under dry and wet redox conditions

Based on rhombohedral structure (R3̄) complex Nd10Mo2O21 compound has proton conductivity ∼8 × 10−4 S cm−1 at 600 °C.

Spectroscopic, thermal and cw dual-wavelength laser characteristics of Nd:LaF3 single crystal

A Nd-doped LaF3 crystal was grown by Czochralski method, and the rocking curves of (002) and (110) diffraction planes show good crystallinity quality of the as-grown crystal. Room-temperature fluorescence spectrum and transmittance spectrum of Nd:LaF3 crystal were investigated, both indicating probable dual-wavelength emissions at ∼1.04μm and ∼1.06μm. The thermal diffusivity and thermal conductivity of Nd:LaF3 crystal were detailed studied. Cw dual-wavelength laser operation of Nd:LaF3 single crystal at 1040nm and around 1065nm with LD pumping was demonstrated. A maximum output power of 302mW was obtained with a slope efficiency of about 18.5% with respect to the pump power. The results of our study indicate the Nd:LaF3 crystal a promising laser crystal.

Spectroscopic, thermal and laser characteristics of Nd:LiLuF4 for 1314 nm laser

Nd-doped LiLuF4 crystal was grown by the traditional Czochralski method. Room-temperature polarized spectroscopic characteristics of Nd3+ ions in LiLuF4 crystal were investigated. The maximum emission cross-sections are 5.45 × 10−20 cm2 at 1320 nm and 2.34 × 10−20 cm2 at 1313 nm for π-polarization and σ-polarization, respectively. The thermal expansion coefficient, specific heat, thermal diffusion coefficient and the thermal conductivity of Nd:LiLuF4 crystal were systematically studied, which, to the best of our knowledge, is the first time for this crystal thus far. Laser operation in an Nd:LiLuF4 single crystal at 1314 nm with laser-diode pumping was demonstrated. We obtained 3.7 W output power at 1314 nm with a slope efficiency of near 32%. The results of our study indicate that Nd:LiLuF4 crystal is a very promising crystal for application as a high-peak power laser.

Experimental analysis of overall thermal properties of Nd:La2CaB10O19crystals

Pure or rare-earth-ion-doped La2CaB10O19(LCB) is a promising optical material for nonlinear frequency conversion, laser and self-frequency doubling applications. In this paper, the thermophysical properties of Nd3+-doped LCB (Nd:LCB) crystals were measured and compared with those of pure and of Yb3+- and Er3+-doped LCB, as well as other borate nonlinear optical crystals. The melting points of rare-earth-doped LCB crystals are lower than that of pure LCB. Thermal expansion coefficients along thea,b,c,c*,a*, 〈110〉 and 〈110〉* directions have been measured, and the principal expansion coefficients were calculated to be 1.85 × 10−6, 4.13 × 10−6and 8.79 × 10−6 K−1. The measured specific heat of Nd:LCB is lower than that of pure LCB, resulting in a larger internal temperature gradient under irradiation by a pulsed laser beam. The measured thermal expansion anisotropy of Nd:LCB is stronger than that of pure LCB. The thermal conductivities of Nd:LCB along thecandc* directions are smaller than those along other crystallographic directions.

Growth and characterization of Nd:Bi12SiO20 single crystal

A Nd:Bi12SiO20 crystal was grown by the Czochralski method. The thermal properties of the crystal were systematically studied. The thermal expansion coefficient was measured to be α=11.42×10−6K−1 over the temperature range of 295–775K, and the specific heat and thermal diffusion coefficient were measured to be 0.243Jg−1k−1 and 0.584mm2/s, respectively at 302K. The density was measured to be 9.361g/cm3 by the buoyancy method. The thermal conductivity of Nd:Bi12SiO20 was calculated to be 1.328Wm−1K−1 at room temperature (302K). The refractive index of Nd:Bi12SiO20 was measured at room temperature at eight different wavelengths. The absorption and emission spectra were also measured at room temperature. Continuous-wave (CW) laser output of a Nd:Bi12SiO20 crystal pumped by a laser diode (LD) at 1071.5nm was achieved with an output power of 65mW. To our knowledge, this is the first time LD pumped laser output in this crystal has been obtained. These results show that Nd:Bi12SiO20 can serve as a laser crystal.

Fabrication and Effects of Different Average Grain Sizes on Thermal Conductivity of Nd:YAG Ceramics

High quality, transparent 1.0at% Nd:YAG ceramics were fabricated successfully by a solid-state reaction and vacuum sintering, and the characteristics were also identified in different methods. The lowest transmittance is 44.85% and the highest is 71.98%. 9 samples were used for thermal diffusivity detecting using laser flash method. Thermal diffusivity decreases as temperature increases, and The diffusivity increases as average grain size grows. However, when average grain size is smaller than 8μm, the diffusivity decreases much faster. Mechanical advantages be ensured, the average grain size should be above 8μm.

Development and application investigation of an ICSHG 532 nm diode-pumped solid-state laser system

A diode-pump solid-state laser system emitting a 532 nm beam has been developed. The pump source is an 808 nm diode laser, which has gained wide acceptance in research as well as in commercial production due to its effectiveness and reasonable price. The active medium was chosen to be Nd:YVO 4 (neodymium-doped yttrium orthovanadate), a material with many advantages over traditional Nd:YAG (neodymium-doped yttrium aluminum garnet) such as a low lasing threshold and linearly polarized beam. However, the thermal conductivity of Nd:YVO 4 is not as good as Nd:YAG, thus the thermal lens effect inside Nd:YVO 4 under high pumping intensity becomes severe and detrimental to the laser performance. Our work showed that careful adjustments of Nd:YVO 4 temperature as well as of the cavity's parameters played an important role in the performance of the laser. Potassium titanyl phosphate (KTP), a nonlinear optics crystal, was used to convert the fundamental 1064 nm laser radiation from Nd:YVO 4 into 532 nm. The 532 nm laser beam has been successfully proven to cut wood, plastic and aluminum.

Electrical conductivity of Nd and Ce co-doped Gd2Zr2O7 ceramics

In this study, (Gd1− x Nd x )2(Zr1− x Ce x )2O7 (0 ≤ x ≤ 0.5) ceramics have been prepared by pressureless sintering at 1973 K to investigate the influence of Nd and Ce co-doping on their electrical conductivity. The electrical conductivity of the ceramics was investigated by impedance spectroscopy measurements from 723 to 1173 K over the frequency range of 20 Hz to 2 MHz in air. The measured values obey the Arrhenius relation. For each composition, the grain conductivity gradually increases with increasing temperature from 723 to 1173 K. At a given temperature, it gradually decreases with increasing neodymium and cerium contents from x = 0 to 0.3; thereafter, the grain conductivity exhibits a slight increase with further increasing neodymium and cerium contents up to x = 0.5.

Sintering, transport properties and thermal expansion of Cr-deficient Nd0.75Sr0.25Cr1−δO3 solid solutions

Abstract Chromium-deficient Nd 0.75 Sr 0.25 Cr 1− δ O 3 (0.02 ≤ δ ≤ 0.06) solid solutions were prepared using a conventional solid-state reaction. The effects of chromium-deficiency content on sintering, transport properties and thermal expansion of the solid solutions were investigated. The results showed that all the solid solutions present single phase orthorhombic perovskite structure at room temperature. The cell volume and the electrical conductivity of Nd 0.75 Sr 0.25 Cr 1− δ O 3 solid solutions decrease with the increase of Cr vacancy content. The Nd 0.75 Sr 0.25 Cr 0.98 O 3 sample exhibits the best properties. The relative density is 95.5%, and the electrical conductivity and thermal expansion coefficient (TEC) reach 18.8 S cm −1 at 850 °C and 9.62 × 10 −6 K −1 in the temperature range of 30–1000 °C in air, respectively. Compared with Nd 0.75 Sr 0.25 CrO 3 , TEC of the Nd 0.75 Sr 0.25 Cr 0.98 O 3 sample is more compatible with that of yttria stabilized zirconia (10.3 × 10 −6 K −1 ). Sintering, electrical and thermal expansion properties all indicate that Nd 0.75 Sr 0.25 Cr 0.98 O 3 can be a promising candidate for interconnect material application in solid oxide fuel cells.

A potential interconnect material for solid oxide fuel cells: Nd 0.75Ca 0.25Cr 0.98O 3− δ

Chromium-deficient Nd 0.75Ca 0.25Cr 1− x O 3− δ (0.02 ≤ x ≤ 0.06) oxides are synthesized and assessed as a novel ceramic interconnect for solid oxide fuel cells (SOFCs). At room temperature, all the samples present single perovskite phase after sintering at 1600 °C for 10 h in air. Cr-deficiency significantly improves the electrical conductivity of Nd 0.75Ca 0.25Cr 1− x O 3− δ oxides. No structural transformation occurs in the Nd 0.75Ca 0.25Cr 1− x O 3− δ oxides in the temperature range studied. Among all the samples, the Nd 0.75Ca 0.25Cr 0.98O 3− δ sample with a relative density of 96.3% exhibits the best electrical conductivity of 39.0 and 1.6 S cm −1 at 850 °C in air and hydrogen, respectively. The thermal expansion coefficient of Nd 0.75Ca 0.25Cr 0.98O 3− δ sample is 9.29 × 10 −6 K −1 in the temperature range from 30 to 1000 °C in air, which is close to that of 8 mol% yttria stabilized zirconia electrolyte (10.3 × 10 −6 K −1) and other cell components. The results indicate that Nd 0.75Ca 0.25Cr 0.98O 3− δ is a potential interconnect material for SOFCs.

Dielectric Anomaly and Electric Conductivity of Nd and Nd/V doped Bi4Ti3O12 Ferroelectric Ceramics

Dielectric Anomaly and Electric Conductivity of Nd and Nd/V doped Bi4Ti3O12 Ferroelectric Ceramics

Effect of substrate strain on lattice structure, electrical resistivity, and optical conductivity of [formula omitted] thin films grown on [formula omitted

In this study, we investigated the lattice structure, electrical resistivity, and optical conductivity of Nd 0.5Sr 0.5MnO 3 thin films grown on SrTiO 3 (001) and SrTiO 3 (011) substrates. The thin film on SrTiO 3 (001) experiences isotropic tensile strain and shows characteristics of the semiconducting ground state. On the other hand, the thin film on SrTiO 3 (011) experiences anisotropic tensile strain, which means that one of the two in-plane lattice axes is fixed by the substrate lattice and the other axis is relaxed. The thin film shows the insulator–metal phase transition at 220 K and characteristics of the charge-ordered insulating ground state below 150 K. By comparing the single crystal data of the lattice along with the resistivity and optical conductivity, we suggest that the substrate strain affects the electronic structure as well as the carrier dynamics of the Nd 0.5Sr 0.5MnO 3 thin films. We propose the possible ground states formed in the thin films.

Effect of Nd doping on structural and thermal properties of Sr 3Ga 2Ge 4O 14 crystals

Nd:Sr 3Ga 2Ge 4O 14 (Nd:SGG) crystals with different Nd 3+ concentrations have been grown by the vertical Bridgman method. The influence of the Nd 3+ concentrations on lattice parameters and thermal conductivity were investigated. The lattice parameters are linear functions of the Nd 3+ concentrations; the structure distortion is relatively small when Nd 3+ concentration is lower than 1.5 at.%. The thermal diffusivity was investigated as a function of Nd 3+ concentrations for the first time; from this, the thermal conductivity of 1.5 at.% Nd-doped SGG crystals was calculated. The results indicate that the thermal conductivity of Nd:SGG is similar to those of laser glasses.

High-throughput characterization of local conductivity of Nd 0.9Ca 0.1Ba 2Cu 3O 7− δ thin film by the low-temperature scanning microwave microscope

We developed a scanning microwave microscope (SμM) designed for high-throughput electric-property screening as well as for rapid construction of electronic phase diagrams at low temperatures. As a sensor probe, we used a high- Q λ/4 coaxial cavity resonator to which a thin needle with ball-tip end was attached. The sensor module was mounted on the low-temperature XYZ stage, which allowed us to map out the change of resonance frequency and quality factor due to the local tip-sample interaction at low temperatures. From the measurements of combinatorial thin films, such as Ti 1− x Co x O 2− δ and Nd 0.9Ca 0.1Ba 2Cu 3O 7− δ (NCBCO), it was demonstrated that this SμM system has enough performance for the high-throughput characterization of sample conductance under variable temperature conditions.

The Thermal Conductivity of Nd2Zr2O7 Pyrochlore and the Thermal Behavior of Pyrochlore‐Based Inert Matrix Fuel.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Thermal conductivity and refractive indices of Nd:GdVO4 crystals

AbstractThe thermal conductivities of Nd:YAG, M(Y,Gd)VO4 crystals were measured at 298 K. The value of Nd:GdVO4 crystal along <001> direction was 11.4 W/mK, which was higher than that of YAG crystal measured to be 10.7 W/mK. The principal refractive indices of Nd:GdVO4 crystal in the temperature range from 20 °C to 170 °C were determined by auto‐collimation method. Based on the measured values of refractive indices, the Sellmeier equation and expression of temperature dependence of refractive indices have been obtained. The measured results show that the birefringence Δn is 0.22007 at 20 °C and temperature coefficient of birefringence is 4.33 × 10−6/°C for 1.064 μm. These results prove that the GdVO4 crystal is a laser crystal with excellent thermal and birefringence properties. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Thermoelectric Properties of Ni‐ and Zn‐Doped Nd2CuO4.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Raman investigation of lattice vibration modes and thermal conductivity of Nd-doped zircon-type laser crystals

The Raman spectra of neodymium-doped yttrium orthovanadate Nd:YVO 4 (NYV) and neodymium-doped gadolinium orthovanadate Nd:GdVO 4 (NGV) have been measured at room temperature with different geometrical configurations. On the basis of the group theory and lattice dynamics theory, all the Raman peaks are assigned, and a correlation between the thermal conductivity and the Raman scattering strength is presented. The thermal conductivity of Nd:GdVO 4 and Nd:YVO 4 crystals along [1 1 0] and [1 0 1] directions are calculated and a good agreement with experimental results is obtained. The higher thermal conductivity of NGV crystal is mainly attributed to the fact that the effective radius of Gd 3+ ion in NGV crystal is close to that of Nd 3+ ion, which in return, enhances the crystal field strength of the laser crystal.

Thermoelectric properties of Ni- and Zn-doped Nd 2CuO 4

The electrical resistivity, Seebeck coefficient, and thermal conductivity of Nd 2(Cu 0.98M 0.02)O 4 (M: Ni and Zn) have been measured in the temperature range from room temperature to about 1000 K. Ni- and Zn-doping decreases the electrical resistivity and the absolute values of the Seebeck coefficient. The thermal conductivity decreases with increasing temperature, showing phonon conduction, and also decreases by doping. The power factor of Nd 2(Cu 0.98Ni 0.02)O 4 reaches 1.02×10 −4 W m −1 K −2 and the figure of merit is 1.35×10 −5 K −1 at 320 K. The relatively low figure of merit compared with that of the state-of-the-art thermoelectric materials is due to the high thermal conductivity.