This work was supported by Natural Science Foundation of China(No.50962004,and No.21061004);Natural Science Foundation of Guangxi(No.0832003Z and No.0832001),and Programs for New Century Excellent Talents in Guangxi(No.2006202).
Two series of B-site deficient perovskites Ba_(5+m)Ti_(m)Nb_(4)O_(15+3m)(m=1,2,3)and Sr_(3+m)LaTi_(m)Nb_(3)O_(12+3m)(m=0,1,2)with the general formula A_(n)B_(n-1)O_(3n)(n=4-8;A=Ba,Sr,La;B=Nb,Ti)have been synthesized,a...