Synergistic influences of titanium,boron,and oxygen on large-size single-crystal diamond growth at high pressure and high temperature

The synergistic influences of boron,oxygen,and titanium on growing large single-crystal diamonds are studied using different concentrations of B_(2)O_(3) in a solvent-carbon system under 5.5 GPa-5.7 GPa and 1300℃-1500℃.It is found that the boron atoms are difficult to enter into the crystal when boron and oxygen impurities are doped using B_(2)O_(3) without the addition of Ti atoms.However,high boron content is achieved in the doped diamonds that were synthesized with the addition of Ti.Additionally,boron-oxygen complexes are found on the surface of the crystal,and oxygen-related impurities appear in the crystal interior when Ti atoms are added into the FeNi-C system.The results show that the introduction of Ti atoms into the synthesis cavity can effectively control the number of boron atoms and the number of oxygen atoms in the crystal.This has important scientific significance not only for understanding the synergistic influence of boron,oxygen,and titanium atoms on the growth of diamond in the earth,but also for preparing the high-concentration boron or oxygen containing semiconductor diamond technologies.

Micro-structured lepidocrocite-type H_(1.07)Ti_(1.73)O_(4)as anode for lithium-ion batteries with an ultrahigh rate and long-term cycling performance

The lepidocrocite-type H_(1.07)Ti_(1.73)O_(4) microsized structures with a tap density of 0.88 g·cm^(-3) were prepared through the ion exchange method with K_(0.8)Li_(0.27)Ti_(1.73)O_(4) powder as the precursor,and they exhibited good rate performance and outstanding cycle stability as an anode material for lithium ion batteries(LIB).The ion exchange method provides favorable conditions for H_(1.07)Ti_(1.73)O_(4) as an anode electrode material for LIBs.X-ray photoelectron spectroscopy(XPS)result demonstrates the existence of defects in the nonstoichiometric H1.07Ti1.73O4,which have a beneficial effect on the LIB performance.The electrochemical performance test proves that the half-cell with microsized H_(1.07)Ti_(1.73)O_(4)as the anode electrode can maintain a specific capacity of 129.5 mAh·g^(-1) after 1100 cycles and 101 mAh·g^(-1)after 3000 long cycles at high current densities of 2.0 and 5.0 A·g^(-1),respectively.In addition,the small volume change rate of 3.6%in H_(1.07)Ti_(1.73)O_(4)during Li ion insertion was confirmed by real-time in situ transmission electron microscopy(TEM).The LiFePO_(4)||H_(1.07)Ti_(1.73)O_(4)full battery exhibits a longterm cycling stability with a specific capacity of73.8 mAh·g^(-1) at a current density of 500 mA·g^(-1) after 200 cycles.

Thermoelectric properties of n-type SiGe alloys with Sn incorporation

In the past several decades,silicon germanium(SiGe)bulk alloys have been a research focus in addressing the current global energy crisis and environmental pollution problems due to their excellent high-temperature thermoelectric properties.In this study,n-type Si_(80)Ge_(20)P_(2)Sn_(x)bulk alloys were fabricated by spark plasma sintering(SPS)to investigate the effect of Sn incorporation.In addition,the optimal sintering conditions and Sn content were determined.The introduction of Sn improves the electrical conductivity and power factor of the n-type SiGe bulk alloys due to the doping and composite effects.Particularly,the Si_(80)Ge_(20)P_(2)Sn_(2)bulk alloy could reach a high figure of merit(ZT)value of~1.26 at 800℃.Thus,this work provides a quick preparation method for obtaining n-type SiGe bulk alloys with outstanding thermoelectric properties by incorporating Sn,which is favorable for large-scale production.