@article{YaoXiaZuoetal.2015, author = {Dongxu Yao and Y. Xia and K.-h. Zuo and Y.-P. Zeng and D. Jiang and Jens G{\"u}nster and J.G. Heinrich}, title = {Gradient porous silicon nitride prepared via vacuum foaming and freeze drying}, journal = {Materials letters}, volume = {141}, pages = {138 -- 140}, doi = {10.1016/j.matlet.2014.11.067}, year = {2015}, }