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Ferrite for Beginners: What is Ferrite?

If you have ever worked with electronics, or simply use electronic devices in your daily life, then it is likely that at some point you have come across ferrite – whether you have noticed or not! In the first part of our series ‘Ferrite for Beginners’ we explored why there is a need for ferrite, particularly when it comes to managing power efficiently. Now we are going to take a closer look at ferrite as a material itself, first exploring how it came to be, before looking at the different types of ferrites that are available.



A Brief History of Ferrite

1930 – Discovery at the Tokyo Institute of Technology

In 1930, the discovery of ferrite marked a significant milestone in the field of magnetic materials, attributed to the collaborative efforts of Dr Takeshi Takei and Dr Yogoro Kato at the Tokyo Institute of Technology in Japan. They discovered ferrite while conducting research on magnetic materials, with a particular interest in materials that could exhibit high electrical resistance and significant magnetic properties.


World War II – Ferrite’s prominence

During World War II, ferrite proved useful for various military applications due to its magnetic properties. It played a crucial role in the development of radar technology, serving as a key component in radar antennas. The development and deployment of radar technology during the war marked a turning point in the use of ferrite, transitioning it from a laboratory discovery to a critical component in military and civilian technologies.


Post-War Era and Beyond

After World War II TDK, Philips (now Ferroxcube), and other companies, including Fair-Rite and Magnetics, continued to innovate and refine ferrite technology. Ferrite became a fundamental material in the production of electronic components such as transformers, inductors, and magnetic cores. These components were integral to the growth of the post-war electronics industry, supporting advancements in telecommunications, computing, and consumer electronics.



What is Ferrite?

Ferrite is a type of ceramic material that is composed mainly of iron oxide (Fe2O3) combined with other metallic elements like manganese, zinc, or nickel. It is a type of metal oxide, and its name is derived from the Latin word “ferrum,” which means iron.

 

Ferrite is known for its magnetic properties, making it useful in various applications related to electronics and electrical engineering. It has a crystalline structure, and its properties come from the alignment of magnetic moments (the strength and direction of a magnet) in its crystal lattice.

 

Ferrites can be categorised into two main types: hard and soft ferrite. Hard and soft ferrites are types of magnetic materials that exhibit distinct magnetic properties, making them suitable for different applications. Let’s look at the differences between hard and soft ferrites, as well as some of their applications.


Hard Ferrites

Hard ferrites, also known as ceramic magnets or permanent magnets, are characterised by their high coercivity and remanence. Coercivity refers to the material’s resistance to demagnetisation, while remanence is the residual magnetisation retained when the external magnetic field is removed. These materials are commonly composed of iron oxide mixed with other elements such as barium, strontium, or lead.



Hard Ferrite Applications

  • Magnets for Electronics: Hard ferrites are widely used in the production of magnets for electronic devices such as speakers, headphones, and microwave components. The stable and strong magnetic properties make them ideal for creating compact and efficient magnetic systems.

  • Magnetic Separators: Hard ferrite magnets are employed in magnetic separators for separating ferrous materials from non-ferrous substances. This is crucial in industries such as mining, recycling, and food processing, where the separation of magnetic and non-magnetic materials is essential.

  • Refrigerator Magnets: The magnets used in refrigerator doors and magnetic whiteboards are often made from hard ferrites. These magnets provide a cost-effective solution for everyday applications where a permanent magnet is needed.

  • Automotive Applications: Hard ferrites are used in various automotive applications, including in electric motors, sensors, and actuators. Their durability and resistance to demagnetisation make them suitable for these demanding environments.

  • Permanent Magnet Motors: Hard ferrites are utilised in the manufacturing of permanent magnet motors used in a range of devices, from small appliances to industrial machinery. These motors benefit from the reliable and long-lasting magnetisation provided by hard ferrites.


Soft Ferrites

On the other hand, soft ferrites possess low coercivity and remanence, allowing them to be easily magnetised and demagnetised. Soft ferrites are primarily used in applications where magnetic flux needs to alternate rapidly, such as in transformers and inductors. The composition of soft ferrites often involves mixtures of iron oxide and other metal oxides, such as manganese, zinc, or nickel. Unlike hard ferrites, soft ferrites are designed to exhibit minimal hysteresis loss and dissipate less energy in the form of heat during the magnetisation and demagnetisation cycles, making them suitable for applications requiring efficient magnetic coupling.



Soft Ferrite Applications

  • Transformers: Soft ferrites are extensively used in the cores of transformers. The ability of soft ferrites to quickly switch magnetic states with minimal energy loss makes them ideal for transformers, where the magnetic field needs to alternate rapidly to induce voltage changes.

  • Inductors: Inductors, which store energy in a magnetic field, often use soft ferrite cores. Soft ferrites help reduce energy losses and heat generation in inductors, making them suitable for applications like power supplies, filters, and chokes.

  • RFID Antennas: Soft ferrites are employed in the manufacturing of antennas for Radio Frequency Identification (RFID) devices. The rapid response of soft ferrites to changing magnetic fields is advantageous in RFID applications where efficient communication between the tag and the reader is crucial.

  • Magnetic Sensors: Soft ferrites find applications in magnetic sensors, such as those used in automotive applications for speed sensing, position sensing, and anti-lock braking systems (ABS). The quick response and low hysteresis loss (energy lost as heat) of soft ferrites contribute to the precision of these sensors.

  • Noise Suppression Devices: Soft ferrites are used in noise suppression components, such as ferrite beads and chokes, to suppress electromagnetic interference (EMI) in electronic circuits. Placing soft ferrite beads on cables can help absorb and decrease high-frequency noise, enhancing the overall performance of electronic devices.


Ferrite - A Versatile Material

Since its discovery in 1930, ferrite has evolved into a key material in the world of electronics. In this blog we have explored what ferrite is and how it can be categorised into two different types – hard and soft. It is important to distinguish these two types of ferrites as they have unique properties which allow them to excel in particular applications. The key is in remembering that hard ferrites have a high resistance to demagnetisation, whilst soft ferrites can easily be magnetised and demagnetised. In the next part of our ‘Ferrite for Beginners’ series, we are going to be looking at some of the key terms that you should understand when referring to the properties of ferrite.

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