Infrared absorption spectra of a Nd0.5Ho0.5Fe3(BO3)4 crystal

Infrared absorption spectra of a Nd_0.5Ho_0.5Fe₃(BO₃)₄ crystal in the spectral range of 30–1700 cm^–1 have been measured at temperatures from 6 to 300 K. The experimental spectra have been analyzed based on the semiempirical calculation of the lattice dynamics and the analysis of correlation diagrams of borate complexes. No changes associated with structural phase transitions have been detected in the temperature range of measurements; the effect of magnetic ordering on the infrared absorption spectra has not been observed.     

Specific heat of YFe3(BO3)4, Y0.5Gd0.5Fe3(BO3)4, and GdFe3(BO3)4

The specific heat was measured in the range 0.4–300 K in YFe₃(BO₃)₄, Y_0.5Gd_0.5Fe₃(BO₃)₄, and GdFe₃(BO₃)₄ single crystals. Sharp anomalies were found at temperatures of first-order structural, second-order antiferromagnetic, and first-order spin-reorientational transitions. A Néel temperature of about 37 K was found to be virtually independent of presence of rare-earth ions, indicating rather weak coupling of Gd and Fe subsystems. The contribution of the magnetic system to specific heat was separated through the scaling procedure allowing determination of the magnetic entropy of Fe and Gd subsystems. At the lowest temperatures, the specific heat in GdFe₃(BO₃)₄ exhibits a Schottky-type anomaly, which is due to Gd³⁺ eightfold degenerate ground-level splitting by the internal magnetic field of the Fe subsystem of about 7 T. The text was submitted by the authors in English.     

New green self-frequency-doubling diode-pumped Nd:Ca4GdO(BO3)3 laser

3+ :Ca₄GdO(BO₃)₃ (Nd:GdCOB). 21 mW of green cw laser emission for an absorbed pump power of 820 mW were achieved under laser diode-pumping. 64 mW of green cw laser output were obtained with 1 W of absorbed pump power under titanium-sapphire pumping. Its availability in large-size crystals with good optical quality makes Nd:GdCOB a true challenger to the best SFD laser crystal reported so far: Nd:YAl₃(BO₃)₄ (Nd:YAB or NYAB). Received: 2 March 1998/Revised version: 20 May 1998     

Excited state absorption and stimulated emission of Nd3+ in crystals III: LaSc3(BO3)4, CaWO4, and YLiF4

3+ ions in CaWO₄, LaSc₃(BO₃)₄, and YLiF₄ crystals are presented. The spectra were measured by a continuous-wave pump and probe technique. It is shown that ESA is a negligible loss mechanism in cw lasers emitting at 1.06 μm. In contrast, the effective emission cross sections in Nd:CaWO₄ and Nd:LaSc₃(BO₃)₄ around 1.35 μm are considerably diminished. Received: 8 May 1998/Revised version: 7 September 1998     

IR active phonons in single crystals RFe3(BO3)4 (R = Pr,Nd, and Sm)

We have studied the reflection and transmission spectra of multiferroics RFe₃(BO₃)₄ (R = Pr, Nd, and Sm) at room temperature. Simulation of reflection spectra by the dispersion-analysis method have allowed us to determine the frequencies and oscillator strengths of the majority of IR active A ₂ and E vibrational modes.     

1180 nm Raman laser operation of end-pumping Nd:GdAl3(BO3)4/SrWO4 crystal

We present an end-pumped continuous-wave Raman laser at 1180 nm with a 60 mm long pure crystal SrWO₄ and an Nd:GdAl₃(BO₃)₄ crystal. The highest output power Raman laser at 1180 nm is 15.5 mW corresponding to the pump power of 1.75 W. Results indicate that the intense self-doubling frequency effect of GdAl₃(BO₃)₄ reduces the 1180 nm Raman laser output.     

Enhanced susceptibility in LNiO3 perovskites ( L = La,Pr,Nd,Nd0.5Sm0. 5)

The temperature dependence of the resistivity rho(T) and of the dc magnetic susceptibility chi(T) were measured on high-quality LNiO3 (L = La,Pr,Nd,Nd0.5Sm0.5) samples synthesized under high oxygen pressure. Subtraction of the rare-earth contribution to chi(T) allows the presentation of the evolution of the susceptibility of the NiO3 array from Pauli to Curie-Weiss paramagnetism with decreasing bandwidth. A metal-insulator transition occurring at a temperature T(t) = T(N) is first order for L = Pr and Nd; it becomes second order and produces no anomaly in chi(-1)(T) at a T(t)>T(N) for L = Nd0.5Sm0.5. In the antiferromagnetic domain T相似文献   

Luminescence and Nonlinear Optical Properties of Borates LnGa3(BO3)4 (Ln = Nd,Sm, Tb,Er, Dy,or Ho)

Optics and Spectroscopy - Luminescence spectra of single crystals of rare-earth gallium borates LnGa3(BO3)4 (Ln = Nd, Sm, Tb, Er, Dy, or Ho) at room (300 K) and cryogenic (10 K)...     

Simultaneous generation of violet,blue, and green lasers using Nd:YAl3(BO3)4 channel waveguides under pumping at 815 nm

Violet, blue, and green lasers were simultaneously generated by nonlinear processes using ultrafast laser inscribed neodymium‐doped yttrium aluminum borate (Nd:YAl₃(BO₃)₄ or Nd:YAB) channel waveguides under pumping at 815 nm. These visible lasers were generated by the frequency doubling, self‐frequency summing, and self‐frequency doubling processes based on a 1062 nm laser radiation that corresponded to the ⁴F_3/2 → ⁴I_11/2 transition of Nd³⁺ ions. Further, the wavelength tunability for the violet and blue lasers was achieved by simply tuning the pump wavelength within the ⁴I_9/2 → ⁴F_5/2 transition. The results obtained indicate that Nd:YAB waveguides are promising candidates for efficient compact visible laser sources. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Self-sum- and -difference-frequency mixing in GdAl(3)(BO(3))(4):Nd(3+) for generation of tunable ultraviolet and infrared radiation

We exploited Nd(3+) laser emission at 1061.9 nm ((4)F(3/2)?(4)I(11/2) channel) in a self-chi((2)) active GdAl(3)(BO(3))(4):Nd(3+) laser crystal. UV radiation was obtained from a 1.8% yield from self-sum-frequency mixing: 1/pump + 1/1061.9 = 1/UV, during pumping in the Nd(3+) (4)G(5/2)-(2)G(7/2) levels near 588 nm. The UV tunability had a range of 378-382 nm. We have demonstrated, for the first time to our knowledge, generation of coherent IR radiation from a self-difference-frequency mixing laser: 1/pump - 1/1061.9 = 1/IR. We got a 0.5% yield and tunability in the 1305-1365-nm range.     

Atomic origin of magnetocrystalline anisotropy in Nd(2)Fe(14)B

The magnetic moment reversal at each of the two inequivalent Nd sites in a single crystal of ferromagnetic Nd(2)Fe(14)B is probed by dichroic resonant diffraction of circularly polarized x rays. The results, supported by theory, show that the c-axis intrinsic magnetic stability of this superior permanent magnetic material arises predominantly at one of the Nd sites (g). The other site (f) undermines magnetic stability by favoring a magnetic moment orientation in the basal plane.     

(Nd1-xErx)3Fe273Ti17化合物的结构与磁性

通过x射线衍射分析和磁性测量对(Nd1-xErx)3Fe273Ti17化合物的结构与磁性进行了研究.单相(Nd1-xErx)3Fe273Ti17化合物的成相范围为x=00—05之间，所有化合物均属于单斜晶系、Nd3(Fe,Ti)29型结构和A2/m空间群.着Er含量的增加，(Nd1-xErx)3Fe273Ti17化合物的晶胞体积、居里温度TC和5K下的饱和磁化强度Ms均单调减小，而5K下的饱和磁化强度Ms和Er含量的关系与稀释模型所描述的结果相一致.(Nd1-xErx)3Fe273Ti1 关键词： (Nd1-xErx)3Fe273Ti17化合物 磁晶各向异性 自旋重取向 磁相图     

Nd:Ca4ReO(BO3)3(Re=Gd,Y)晶体最佳激光、最佳倍频及最佳自倍频方向的确定

介绍了Nd:Ca4ReO(BO3)3(Re=Gd,Y)晶体最佳激光方向、最佳倍频方向的确定.综合考虑激光受激发射截面、抽运光吸收系数、有效非线性系数的各向异性,分析了自倍频性质的空间分布,并就此确定出最佳自倍频方向 关键词： Nd:Ca4ReO(BO3)3(Re=Gd Y)晶体 激光发射 倍频 自倍频     

Nd0.5Ca0.5Mn1-xAlxO3 (x=0,0.03)体系中电荷有序态的超声研究

系统研究了Nd0．5Ca0．5Mn1-xAlxO3(x=0,0．03)单相多晶样品在低温下的电磁性质和超声特性．电阻和磁化率测量表明,Nd0．5Ca0.5O3体系在TCO-257 K处发生了电荷有序相变．超声声速从室温开始随着温度的降低逐渐减小,并在TCO附近达到最小,之后,随着温度的进一步降低,声速急刷增加,同时伴随着一个尖锐的超声衰减峰出现.TCO附近的超声异常表明体系中存在着强烈的电-声子相互作用,该电-声子耦合来源于Mn3 的Jahn-Teller效应．在低温下,出现了另一个超声衰减峰,它的出现归结为反铁磁相与顺磁相之间的相分离现象.随着Al在Mn位的掺入,超声声速的最低点和衰减峰向低温移动,表明体系中的电荷有序态和反铁磁相均被部分抑制,     

Shear strain in Nd0.5Ca0.5MnO3 at high pressures

High-pressure x-ray powder diffraction has been measured on the half doped rare earth manganite Nd0.5Ca0.5MnO3 up to a pressure of 15 GPa. We report the presence of a quantifiable amount of shear distortion of the MnO6 octahedra in Nd0.5Ca0.5MnO3 at high pressures. The lattice strain of Nd0.5Ca0.5MnO3 is minimal at a crossover pressure of p* approximately 7 GPa, with the same lattice strain above and below this pressure achieved by shear and Jahn-Teller-type distortions, respectively. The increase in shear strain with increasing pressure provides a mechanism for the insulating behavior of manganites at high pressures that has not been considered before.     

A 180 mW Nd:LaSc3(BO3)4 single-frequency TEM00 microchip laser pumped by an injection-locked diode-laser array

A TEM₀₀ single-frequency, diode-pumped microchip laser of Nd(25%):LaSc₃(BO₃)₄ is operated with an output power of 180 mW. For best performance the laser was pumped by the 450 mW diffraction-limited single-frequency radiation of an injection-locked AlGaAs diode-laser array and cooled to the temperature of liquid nitrogen. The active and passive losses of the microchip laser were investigated by measuring the relaxation oscillation frequency and by comparing the experimental results with values obtained from appropriate rate equations. The power-dependent far-field pattern is in good agreement with the intensity distribution calculated by assuming a thermally induced waveguide cavity.     

Intracavity frequency-doubled diode-pumped Nd : LaSc3(BO3)4 lasers

 An intracavity frequency-doubled 10%Nd : LaSc₃(BO₃)₄ (Nd : LSB) laser was investigated in different resonator configurations and in different operation modes under continuous wave (cw) and quasi-cw laser-diode pumping. With a Cr⁴⁺ : YAG passive modulator and a KTP crystal the second-harmonic output power at 531 nm amounted to 190 mW in Q-switched TEM₀₀ mode at 750 mW of pump power. In a sandwich resonator, when all the optical elements were in direct contact with each other, 0.8 W of green output power was obtained in cw mode under 2.7 W of pump power with a slope efficiency of 44%. In the same setup under fiber-coupled diode-laser array pumping (5.6 W of incident power), 1.2 W of green output power was achieved in cw mode and 1.4 W in quasi-cw mode. Received: 30 April 1996/Revised version: 1 July 1996     

Spectroscopic investigation of rare-earth chromium borates RCr3(BO3)4 (R = Nd, Sm)

The optical absorption spectra of single crystals of neodymium and samarium chromium borates are studied. A magnetic phase transition in NdCr₃(BO₃)₄ (at T _c = 8 ± 1 K) and SmCr₃(BO₃)₄ (at T _c = 5 ± 1 K) is observed. The effective magnetic field acting on the Nd³⁺ ion from the side of the ordered magnetic subsystem of chromium is estimated.     

YAlO3：（Nd^3＋,Lu^3＋）单晶的各向异性吸收光谱

在室温下测量了ＹＡｌＯ３：（Ｎｄ＾３＋，Ｌｕ＾３＋）单昌三个晶轴方向的吸收光谱。其吸收谱带强度明显呈各向异生。将Ｊｕｄｄ－Ｏｆｅｌｔ理论加以修正，并扩展应用于处理各晶轴方向的吸收光谱。     

Nd∶NaR(WO_4)_2晶体生长(R=Bi,Y)

采用提拉法生长出了掺钕钨酸铋钠[Nd∶NaBi(WO4)2,简称Nd∶NBW]和掺钕钨酸钇钠[Nd∶NaY(WO4)2,简称Nd∶NYW]晶体,并给出了制备无开裂优质Nd∶NBW和Nd∶NYW晶体的最佳生长工艺参数。从XRD分析得到Nd∶NBW和Nd∶NYW晶体的晶胞参数,并分析了晶体的拉曼光谱,认为二者结构基本相同,为四方晶系、白钨矿结构、I41/a空间群。由吸收光谱可以看出,Nd∶NBW在802nm有较强的吸收峰,Nd∶NYW在804nm、752nm、586nm附近有较强、较宽的吸收峰,二者均适合于LD泵浦;计算了晶体中Nd3+的吸收截面积。