Hui Shen

Shanghai Institute of Technology · School of Materials Science and Engineering

Discovery of novel functional materials is the cornerstone of spintronics and other emerging technologies. We report an abrupt spin reorientation transition from Γ4(Gx, Ay, Fz) to Γ2(Fx, Cy, Gz) in Dy0.7Nd0.3FeO3 single crystal that combines the Morin transition characteristics of DyFeO3 and the Γ2 spin configuration of NdFeO3. The Γ2 transition al...

In this paper, a series of Gd1-xBixFeO3 (x = 0, 0.1, 0.3, 0.5, 0.7, 0.9, 1) nanoparticles have been readily synthesized by a green and facile sol–gel method. It gradually changed from the orthorhombic structure (space group Pbnm) to the rhombohedral perovskite structure (space group R3c). Weak ferromagnetic behavior was effectively induced by Bi3+,...

Rare-earth orthoferrites have attracted intensive attention in the last few years for abundant physical capabilities. In the present paper, Nd3+ doped Dy0.9Nd0.1FeO3 (DNFO91) single crystal with high quality was grown...

Metal halide perovskites are demonstrated to show fascinating optical and electronic properties, including highly efficient luminescence, outstanding carrier transport behavior, and large light absorption coefficient. In particular, halide perovskite single crystals are characterized with superior optoelectronic performance and enhanced stability,...

Bi³⁺ and Ce³⁺ substituted rare-earth iron garnet is famous magneto-optical material for the application in integrated optical system and microwave devices. Nevertheless, the modulation of Bi³⁺ and Ce³⁺ on the structure and magnetic behavior of terbium iron garnet (TIG) is not very clear, which limits its practical applications. Herein, a series of...

GaAs crystals are important III–V compound semiconductor materials and the bandgap and quantum efficiency can be optimized by doping. However, the doping may bring some problems to the crystal growth. In this paper, Si‐doped GaAs crystals are grown by the modified vertical Bridgman method and the influence of Si doping on dislocations and mechanica...

Relaxor-based ferroelectric PZN-PT crystals are well known with excellent piezoelectric properties. However, the inhomogeneity has been usually observed in this system, which are closely related to its complicated domain structures and phase transitions. In this work, 0.91PZN-0.09PT crystals have been grown by the flux-Bridgman method. The evolutio...

Lead halide perovskites display remarkable optoelectronic properties, like large absorption coefficients, high photoluminescence quantum efficiencies, and long lifetime and diffusion length of photocarriers. This system is easily fabricated using solution processes and inkjet printing is an effective way to prepare halide perovskite films and compl...

Rare earth garnet (R3Fe5O12, RIG) single crystals are the most ideal magneto-optical medium for optical isolators for wavelength longer than 1.1 μm, which has been commercially used in optical fiber communications. However, it is still a great challenge to grow large size RIG single crystals. In this work, high quality YIG (Y3Fe5O12) and Bi:TIG (Bi...

Lithium niobate crystals have excellent photorefractive properties and possess a great development promising in holographic applications. Doping ions with variable valences is of great importance to adjust their photorefractive properties. A series of 1 inch uranium dioxide doped LN crystals with 11 cm in length had been grown successfully by the m...

High quality PrF3 crystal was successfully grown by the temperature gradient technique (TGT). The magneto-optical properties of PrF3 crystal were systematically investigated in the UV-VIS-NIR region. The advantage of PrF3 over CeF3 and TGG is its transparency in deep-UV region down to 258 nm. The dispersions of Verdet constant of PrF3 and TGG cryst...

PrF3 crystals are excellent paramagnetic magneto-optical materials. In this paper we report on the PrF3 complex refractive index and the complex permittivity in terahertz (THz) frequency range. Measurements have been performed using transmission time domain terahertz spectroscopy (THz-TDS). The influence of temperature on the complex refractive ind...

A series of LiNbO3 crystals doped with various MgO concentrations (0, 3%, and 5 mol%) was simultaneously grown in one furnace by the modified vertical Bridgman method. The wet chemistry method was used to prepare the polycrystalline powders, and the growth conditions were optimized. The full width at half maximum of high-resolution X-ray rocking cu...

In this paper, multiple magnetic transitions of Sm0.5Pr0.5FeO3 single crystal were systematically studied. By substituting Pr³⁺ in SmFeO3, spin reorientation temperature (TSR) was effectively decreased from 450 K–480 K (SmFeO3) to 180 K–220 K (Sm0.5Pr0.5FeO3). When the applied magnetic field is 500 Oe, spin switching was observed at 119 K (Tssw) fo...

SnSe has attracted increasing attention as a promising thermoelectric material. In this work, a horizontal vapor transfer method was developed to synthesize high-quality, fully dense, and stoichiometric SnSe single crystals, which enables an evaluation of the transport properties inherent to SnSe along the bc-plane. The electronic transport propert...

In this wok, a novel multi-crucible Bridgman method is developed to produce the Ø 2 inch Si-doped GaAs crystals. Five placements are designed in the furnace means five ingots could be produced at the same time. Twinning and high dislocation density are the main growth defects that often take place in the crystals. After the solid-liquid interface a...

A Horizontal Bridgman (HB) method was employed attempt to grow large size undoped SnSe single crystal. SnSe was crystallized under 2–3 °C/cm temperature gradient and cooled to room temperature at a rate of ∼25 °C/h to release thermal stress. SnSe crystals grown from liquid solution and volatilized vapor were obtained simultaneously. Two single crys...

SnSe-based single crystal has attracted much attention due to its outstanding thermoelectric behaviors, however, the fabrication of large size crystal seems difficult as it is very easy to cleavage during crystal growth. In this work, a novel horizontal Bridgman method was employed to produce SnSe crystal with 3 mol% Ag substitute for Sn. The Sn0.9...

http://scitation.aip.org/content/aip/journal/apl/110/2/10.1063/1.4973993 Rare earth phosphors have been widely studied because of their sharp emission lines and excellent optical performance. However, photoluminescence (PL) tuning by crystal field in Er3+ embedded phosphors has always been a challenge. Here, we demonstrate that pressure can help t...

High quality YFe0.8Mn0.2O3 single crystal of about 45 mm in length and 5 mm in diameter was successfully grown by optical floating zone method. Both powder X-ray diffraction and Laue photograph confirmed the homogeneity and high quality of the sample. The magnetic properties of the specimen are studied under ZFC and FC modes over a wide temperature...

High quality YFe0.6Mn0.4O3 single crystal was grown by floating zone technique using a four-mirror-image-furnace under flowing air. Powder X-ray diffraction gives well evidence that the specimen has an orthorhombic structure,withspace group Pbnm.Temperature dependence of the magnetizations of YFe0.6Mn0.4O3 single crystal were studied under ZFC and...

In this work, we report the structure and magnetic properties of DyFe0.6Mn0.4O3, which crystallizes in orthorhombic perovskite structure with a space group of Pnma. For DyFe0.6Mn0.4O3, a spin reorientation transition, from the canted antiferromagnetic (AFM) state to a collinear AFM state, is found to occur around 310 K, which is remarkably higher t...

(1-x)Pb(Zn1/3Nb2/3)O3-xPbTiO3(PZN-PT) has attracted large attention due to its ultrahigh piezoelectric and dielectric properties. However, its piezoelectric properties fluctuate due to its multiphase coexistence and complicated domain structures. The phase transition at high temperatures is still confusing. In present work, the phase transition was...

A 0.93Pb(Zn1/3Nb2/3)O3–0.07PbTiO3(PZN–PT) single crystal was grown using the flux Bridgman method and 〈0 0 1〉-oriented slides were obtained. Strip-shaped and needle-shaped domains were observed in the same PZN–PT sample by a polarizing microscope. Raman spectra and transmittance spectra of regions with different domain structures have been measured...

The spin reorientation of ErFeO3 that spontaneously occurs at low temperature has been previously determined to be a process involving the continuous rotation of Fe3+ spins. In this work, the dynamic process of spin reorientation in ErFeO3 single crystal has been investigated by AC susceptibility measurements at various frequencies and static magne...

In the present work, the long afterglow luminescent materials of Eu, Dy-doped Ca2MgSi2O7 were fabricated by solid-state reaction or combustion synthesis method, respectively. The samples were characterized by X-ray Diffraction (XRD), Photo Luminescence spectra (PL) and Scanning Electron Microscope (SEM). The effects of the composition of reactants...

YFeO $_{\boldsymbol 3}$ and other rare earth substituted crystals with distorted orthorhombic pervoskite-like structure (space group, Pbnm) have attracted much attention due to their remarkable magnetic properties of primary significance for technological applications. In the present work, the floating zone growth of YFeO $_{\boldsymbol 3}$ cryst...

High purity Mn doped YFeO3 nanocrystals were readily prepared by sol–gel combustion method, with citric acid as the fuel. The doping effect on the structure and magnetic properties was systematically studied. X-ray diffraction and TEM results indicate that the samples are well crystallized. Orthorhombic YFeO3 crystallites can be obtained when calci...

CoFe2O4 ferrites were synthesized sol–gel with cobalt chloride, ferric chloride and citric acid as the main raw material. X-ray diffraction, vibrating sample magnetometer and simultaneous thermal analysis were applied to character the structure and magnetic properties of traditional and microwave calcined samples. The samples with pH 5 and molar ra...

Transparent ZnO crystals were obtained by the flux Bridgman method from high temperature solution of 22 mol% ZnO-78 mol% PbF2 system. The influence of annealing temperatures on the photoluminescence (PL) of ZnO crystal was investigated. An ultraviolet emission peak at about 379 nm was observed in PL spectra and the peak position has a weak blueshif...

Mn-doped ZnO single crystals have been grown by the flux-Bridgman method from a high temperature solution of 24% ZnO-76% PbF2 (molar fraction). A fast nucleation was induced by the gas-cooling system at the bottom of the Pt crucible. A red Mn:ZnO crystal up to 13 mm×15 mm×(3–4) mm was obtained. Powder XRD patterns showed that the as-grown crystals...

The rare-earth orthoferrites RFeO3 (R, rare-earth element) crystallize in an orthorhombic distorted perovskite structure. RFeO3 compounds exhibit interesting physical and chemical properties because of their ionic and electronic defects. Polycrystalline nano-sized RFeO3 powders were synthesized by the sol–gel combustion method. X-ray powder diffrac...

Langasite-type piezoelectric single crystal Sr3NbGa3Si2O14 (SNGS) 25 mm in diameter and 60 mm in length has been grown by the modified vertical Bridgman method. A <0 0 1>-oriented SNGS seed was used and the growth conditions were optimized. The dielectric constants of SNGS crystal show high temperature stability. With increased specific heat, SNGS...

Autocombustion of citric acid gel was employed to prepare ReFeO3 (Re = Gd, Nd) nanocrystalline powders. The phase identification and lattice parameters were investigated by the X-ray diffraction (XRD). Field-emission scanning electron microscopy (FESEM) investigations were carried out to examine the morphology and average size of these powders. Sev...

Nano-crystalline LaFeO3 was synthesized by a sol–gel auto-combustion method from a mixed aqueous solution of lanthanum and iron nitride, using citric acid as the fuel. Powder X-ray diffraction and TG/DTA analysis show that the LaFeO3 crystallites can be directly obtained by the sol–gel combustion process, without any other undesired phase. The resu...

In this work, we reported the magnetic and thermal properties of perovskite YFeO3 crystal grown by the floating zone method. YFeO3 crystal is a canted antiferromagnet with a weak ferromagnetic behavior. The magnetization varied nonlinearly from 0.204emu/g to 0.173emu/g at the temperature range of 2–300K. Its Néel temperature is around 644.5K. The s...

Novel relaxor ferroelectric crystal 0.93Pb(Zn1/3Nb2/3)O3-0.07PbTiO3 (PZNT93/7) with dimensions about Ø40× 70 mm3 was obtained by directional solidification technique. The growth defects of the crystal were investigated. Rocking curve analysis revealed the crystalline quality of PZNT93/7 crystal was not perfect and the FWHM value was measured to be...

The domain structures in 0.93Pb (Zn1/3Nb2/3)O3-0.07PbTiO3 (PZNT93/7) crystals were investigated by chemical etching technique. Original antiparallel 180° domains of size 20–40 μm were observed on the surface of as-grown PZNT93/7 crystal. It was found the domain states are sensitive to the stress field induced by mechanical processing or impurities....

Nd:Sr3Ga2Ge4O14 (Nd:SGG) single crystals up to ∅25 mm × 50 mm were grown by the modified Bridgman method. Absorption and fluorescence spectra of Nd:SGG crystals were measured at room temperature. Compared with Nd:YAG crystals, the absorption of Nd:SGG single crystals presented broad absorption bands of Nd3+ ions. The fluorescence inten- sity increa...

Novel relaxor ferroelectric single crystal (1−x)Pb(Zn1/3Nb2/3)O3–xPbTiO3 (PZNT) was grown by vertical Bridgman method, the mechanical properties of the (111) face were systematically researched using microindentation technique. It was found that the Vickers’ microhardness Hv was as a function of the applied load. In the range of 0.1–3kg, Hv was dec...

The floating zone growth of magneto-optical crystal YFeO3 has been investigated. The polycrystalline feed rod was prepared by a pressure of 250MPa and sintering at about 1500°C. A crack- free YFeO3 single crystal has been successfully grown. The crystal preferred to crystallize along direction with about 10° deviation. The X-ray rocking curve of th...

Neodymium doped strontium gallogermanate crystals were grown successfully by the Bridgman technique. The linear thermal expansion coefficients for the c- and a-axes were measured as 5.8 × 10−6 °C−1 and 6.5 × 10−6 °C−1. Absorption spectra, and fluorescence spectra, as well as fluorescence decay curves of Nd3+-doped Sr3Ga2Ge4O14 crystal, have been re...

A new piezoelectric single crystal, Sr3Ga2Ge4O14 (SGG), has been grown successfully by the vertical Bridgman method with crucible-sealing technique. SGG crystal up to 2″ in diameter has been obtained. The relative dielectric constants, the piezoelectric strain constants, elastic compliance constants and electromechanical coupling factors have been...

ZnO single crystal has been grown from 22 mol%ZnO-78 mol%PbF2 high temperature solution in a homemade vertical Bridgman furnace. The macro growth defects, such as growth striations, boundary, negative crystal, bubbles, and inclusions, were investigated by optical microscopy and an electron probe X-ray microanalyser (EPMA). The formation mechanisms...