US EPA

3152488 

Journal Article 

External stimulation-controllable heat-storage ceramics 

Tokoro, H; Yoshikiyo, M; Imoto, K; Namai, A; Nasu, T; Nakagawa, K; Ozaki, N; Hakoe, F; Tanaka, K; Chiba, K; Makiura, R; Prassides, K; Ohkoshi, S 

2015 

1 

Nature Communications
EISSN: 2041-1723 

6 

7037 

English 

25962982 

10.1038/ncomms8037 

Commonly available heat-storage materials cannot usually store the energy for a prolonged period. If a solid material could conserve the accumulated thermal energy, then its heat-storage application potential is considerably widened. Here we report a phase transition material that can conserve the latent heat energy in a wide temperature range, T<530 K and release the heat energy on the application of pressure. This material is stripe-type lambda-trititanium pentoxide, λ-Ti3O5, which exhibits a solid-solid phase transition to beta-trititanium pentoxide, β-Ti3O5. The pressure for conversion is extremely small, only 600 bar (60 MPa) at ambient temperature, and the accumulated heat energy is surprisingly large (230 kJ L(-1)). Conversely, the pressure-produced beta-trititanium pentoxide transforms to lambda-trititanium pentoxide by heat, light or electric current. That is, the present system exhibits pressure-and-heat, pressure-and-light and pressure-and-current reversible phase transitions. The material may be useful for heat storage, as well as in sensor and switching memory device applications.