Measurement of phase equilibria in Ti-Ni-Sn system

Phase relations of the Ti-Ni-Sn ternary system were investigated via alloy sampling assisted with X-ray diffractometry(XRD)and electron probe micro-analysis(EPMA).A new binary phase with composition of TiSn4(molar fraction,%)was detected at 508 K.In addition,a supplementary phase(Ti1-x-yNixSny)Ni3(τ,AuCu3-type)was observed at 873 and 973 K.According to the characterised microscopic structure in various annealed alloys,four ternary phases were detected in Ti-Ni-Sn ternary system:TiNiSn,TiNi2Sn,Ti2Ni2Sn and(Ti1-x-yNixSny)Ni3.Additionally,isothermal sections of Ti-Ni-Sn ternary system at 508,873 and 973 K were constructed.By comparing three isothermal sections,a peri-eutectic reaction,L+TiNi2Sn→Ni3Sn4+TiNiSn,was deduced,which occurs at a temperature between 873 and 973 K.Furthermore,the solubility of Sn in TiNi and Ni in Ti5Sn3 was detected.

Crystal structures and elastic properties of Ti(Cu,Pt)2 and Ti(Cu,Pt)3 phases

This paper focused on the crystal structures of two new ternary phases,Ti(Cu,Pt)2 and Ti(Cu,Pt)3,which were studied by X-ray powder diffraction data using Rietveld method.Electron probe microanalysis was used for sample composition examination.Elastic properties of these phases were further measured by nano-indentation,and meanwhile calculated with first-principle(FP)calculations.It is found that the crystal structure of Ti(Cu,Pt)2 is of orthorhombic cell space group Amm2(No.38)with structural prototype of VAu2.The resolved structure of Ti(Cu,Pt)3 is of tetragonal Al Pt3 type,belonging to the space group P4/mmm(No.123).The nano-indentation measurement and FP calculations show that the elastic modulus of Ti(Cu,Pt)2 increases firstly then decreases with Pt content,whereas that of Ti(Cu,Pt)3almost linearly increases with Pt content.

Phase equilibria in Ti-Ni-Pt ternary system

Phase equilibria in Ti?Ni?Pt ternary system have been experimentally determined through diffusion triple technique combined with alloy samples approach.Assisted with electron probe microanalysis(EPMA)and X-ray diffraction(XRD)techniques,isothermal sections at 1073 and 1173 K of this system were constructed and existence of ternary phase Ti2(Ni,Pt)3 was confirmed.In addition,binary compounds Ti3Pt5 and TiPt3-were found to be stable at 1073 and 1173 K,and remarkable ternary solubility in some binary compounds was detected,e.g.,solubility of Pt in TiNi can be up to about 36%(molar fraction)at 1073 K and 40%(molar fraction)at 1173 K.Furthermore,a ternary invariant transition reaction TiNi3+Ti3Pt5→Ti2(Ni,Pt)3+TiPt3+at a temperature between 1073 and 1173 K was deduced.

Achieving broadband near-infrared luminescence in Cr^(3+)-Activated Y_(2)Mg_(2)Al_(2)Si_(2)O_(12)phosphors via multi-site occupancy

Cr^(3+)-activated near-infrared(NIR)phosphors are key for NIR phosphor-converted light emitting diodes(NIR pc-LED).While,the site occupancy of Cr^(3+)is one of the debates that have plagued researchers.Herein,Y2Mg2Al2-Si_(2)O1_(2)(YMAS)with multiple cationic sites is chosen as host of Cr^(3+)to synthesize YMAS:xCr^(3+)phosphors.In YMAS,Cr^(3+)ions occupy simultaneously Al/SiO4 tetrahedral,Mg/AlO6 octahedral,and Y/MgO8 dodecahedral sites which form three luminescent centers named as Cr1,Cr2,and Cr3,respectively.Cr1 and Cr2 relate to an intermediate crystal field,with transitions of^(2)E→^(4)A_(2)and^(4)T_(2)→^(4)A_(2)occurring simultaneously.As Cr^(3+)concentration increases,the^(4)T_(2)→^(4)A_(2)transition becomes more pronounced in Cr1 and Cr2,resulting in a red-shift and broadband emission.Cr3 consistently behaves a weak crystal field and exhibits the broad and long-wavelength emission.Wide-range NIR emission centering at 745 nm is realized in YMAS:0.03Cr^(3+)phosphor.This phosphor has high internal quantum efficiency(IQE?86%)and satisfying luminescence thermal stability(I423 K?70.2%).Using this phosphor,NIR pc-LEDs with 56.6 mW@320 mA optical output power is packaged and applied.Present study not only demonstrates the Cr^(3+)multi-site occupancy in a certain oxide but also provides a reliable approach via choosing a host with diverse cationic sites and local environments for Cr^(3+)to achieve broadband NIR phosphors.