日本开发出能够在弱压条件下释放储热的新材料

日本东京大学的研究人员开发出了一种能够长时间存储热能的新型材料，他们将这种材料称为储热瓷(heat storage ceramic)。这是一种可以用作太阳能热发电系统或有效利用工业余热，能够使热能循环利用的储热材料，因为这种材料在弱压力条件下就能释放出存储的热能。

能够储热的材料包括砖或混凝土，能够缓慢地释放储存的热量，而其他材料如水或乙二醇，当它们从固态转换成液态的时候会吸收热量。但是，这些材料中没有一个能够长时间的储存热能，因为他们会随着时间缓慢地、自然地释放热量。一种能够长时间储存热能并在指定的时间里释放热量的材料，对于可再生能源领域来说是一个福音。

日本东京大学研究生院Ohkoshi教授的研究团队开发了这种能够长时间存储热能的储热瓷(heat storage ceramic)。这个材料，被称为条状λ五氧化三钛，仅由钛原子和氧原子组成，能够吸收和释放大量的热能(230 kJ L-1)。存储的热能量非常大，相当于与在熔点的水的70%相变储能。此外，弱压力条件下，60 MPa (mega Pascal)就促使条状λ五氧化三钛相变成β五氧化三钛，释放出存储的热量。除了直接应用热能，热量也能够被储存，以通过材料的电流或用光照射的方式，通过各种方法促使材料反复吸收和释放热量。

条状λ五氧化三钛是一种简单的氧化钛，蕴藏量丰富的元素而且很环保。目前储热瓷(heat storage ceramic)有望成为太阳能发电系统中应用的新材料，欧洲国家正在积极地推动其应用，而且它还能有效利用工业余热。这种材料还能在高级电子设备中应用，如压敏片，可重复利用的加热垫，压敏导电传感器，电流驱动型电阻随机存取存储器(ReRAM)，和光存储器等。

New material releases stored heat under weak pressure

Researchers at the University of Tokyo have discovered a new type of material which stores heat energy for a prolonged period, which they have termed a "heat storage ceramic." This new material can be used as heat storage material for solar heat energy generation systems or efficient use of industrial heat waste, enabling recycling of heat energy, since the material releases the stored heat energy on demand by application of weak pressure.

Materials capable of storing heat include those such as bricks or concrete that slowly release the stored heat, and others such as water or ethylene glycol that take in heat when they transform from a solid to a liquid. However, none of these materials can store heat energy over a long period as they naturally release it slowly over time. A material that could store heat energy for a long time and release it at the exact timing desired would be a boon for the field of renewable energy.

The heat storage ceramic discovered by the research group of Professor Ohkoshi at the University of Tokyo Graduate School of Science preserves heat energy for a prolonged period. This material, called stripe-type-lambda-trititanium-pentoxide, is composed of only titanium atoms and oxygen atoms, and can absorb and release a large amount of heat energy (230 kJ L-1). This heat energy stored is large at approximately 70% of the latent heat energy of water at its melting point. Additionally, applying a weak pressure of 60 MPa (mega Pascal) to stripe-type-lambda-trititanium-pentoxide induces a phase transition to beta-trititanium-pentoxide, releasing the stored heat energy. Besides direct application of heat, heat energy can be stored by passing an electric current through the material or irradiating it with light, enabling the repeated absorption and release of heat energy by a variety of methods.

Stripe-type-lambda-trititanium-pentoxide is a simple titanium oxide composed of abundant elements and is environmentally friendly. The present heat-storage ceramic is expected to be a new candidate for use in solar heat power generation systems, which are actively promoted nowadays by European countries, and also for efficient use of industrial heat waste. This material also has possibilities for use for advanced electronic devices such as pressure-sensitive sheets, reusable heating pads, pressure-sensitive conductivity sensors, electric current driven type resistance random access memory (ReRAM), and optical memory.